As noted in the first part of this review, Windows Phone 7.5 consists of hundreds of new features, spread out across the system. As such, many of these changes are relatively minor, which is to be expected. But Windows Phone 7.5 does include a number of big ticket items as well. And in this second part of my Windows Phone 7.5 review, I'd like to focus on the major new features in "Mango."

Twitter and LinkedIn integration

Conceptually, the biggest difference between Windows Phone and the competition is this notion of integrated experiences, where you visit a central Pictures hub for all of your photo needs, or a central Music + Videos hub for those needs, instead of a slew of separate, potentially widely distributed apps for either. In the initial release of Windows Phone, Microsoft offered two major integration points for social networking services: Windows Live and Facebook. Now, in Windows Phone 7.5, that's being expanded dramatically with similar integration for both Twitter and LinkedIn. (Facebook and Windows Live integration is also improved; this is described later in the review.)

As with Windows Live and Facebook, Twitter and LinkedIn integration begins in Email + Accounts settings, where you configure your account and then watch information associated with either propagate throughout the phone where it makes sense. In the case of Twitter, which I use on a daily basis, this involves optionally adding your followers as contacts to the People hub (which can be ponderous if you have too many followers), sharing photos from the Pictures hub, and integration with the Me tile, from which you can check-in, post a message, or view notifications, which are tweets in which you've been mentioned. You can of course also respond to tweets directly from the Notifications page of the Me tile.

This integration is nicely done but is sadly not as full-featured as it could be. For example, if you're a heavy user of hash tags, the integrated functionality has no understanding of that. So you can manually type in a hash tag, but it won't auto-complete as it does with desktop Twitter clients. And there's no way to access direct messages from the integrated Twitter experience. I end up using a third party Twitter app occasionally--either Rowi or the official app--to take up the slack.

Internet Explorer 9

One of the legitimate complaints about the initial version of Windows Phone is that its web browser is lackluster at best, with a fairly dated rendering engine and only a basic UI. Both of these issues have been addressed in WP 7.5, which features a new web browser, Internet Explorer 9 Mobile. And this isn't IE 9 in name only: It features the same rendering and script engines as its desktop brother and is thus highly compatible with modern, HTML 5-based web sites. This is a big deal in the mobile world, especially, since many sites are catering to popular WebKit-based mobile browsers like Safari (iOS) and the Android web browser, and IE 9 Mobile can generally render these sites very accurately.

IE 9 Mobile is also very fast, thanks to the same sort of GPU hardware-accelerated text, video, and graphics rendering capability that's provided by the desktop version of IE 9.

The already-minimal IE user interface is made even more minimal in this release, too, giving more onscreen real estate to the content you're viewing. Where IE Mobile previously had a top-mounted Address Bar and then an App Bar on the bottom with a few buttons, IE 9 Mobile has only a single area of chrome at the bottom which combines the Address Bar with a pop-up menu featuring various options. These options--Recent, Tabs, Favorites, Add to Favorites, Share Page, and Pin to Start--are carried over from the previous version, but there are handful of new settings to explore.

Also new to IE 9 Mobile is the availability of this UI chrome in landscape mode. In the initial version of Windows Phone, that wasn't available, so you had to keep switching back to portrait if you needed to type in a web address or access some other feature.

Email improvements

While the Windows Phone Mail app has always been excellent, with beautiful typography and a wonderful, easy-to-use user interface, the initial version was lacking a few crucial features. These issues have all been fixed in WP 7.5, and the result is the best email application on any mobile platform.

So now you can link email Inboxes, like the big boys. But in keeping with the Windows Phone way of exceeding what the competition is doing, you can also maintain separate individual inboxes as well as separate linked inboxes, and can in fact have any combination of the two. That's because Windows Phone creates a new instance of the Mail app for each email account. So you could have a version of Mail that links, say, Gmail and Hotmail because those are personal accounts. And your Exchange inbox could be kept separate.

As with Microsoft's desktop and web-based email solutions, Windows Phone 7.5 supports the handy Conversation View, allowing you to view and manage all of the emails in a conversation thread as a single entity. You can tap to the left of the conversation to expand and contract it, which provides a way to multi-select for moving or deleting, or find particular messages. It's so natural that it's hard to believe it hasn't been there all along.

Finally, WP 7.5 also lets you arbitrarily pin any email folder to the Start screen so you can quickly access an email location you frequently access.

Bing improvements

Microsoft somewhat controversially linked its Bing search service to the hardware Search button that all Windows Phone handsets must include, and that tradition continues in Windows Phone 7.5. In fact, if anything, Bing is even more tightly connected to the Search button in this release since Microsoft has moved all internal app searching capabilities from the button to software buttons in-app. So Bing has it all to itself.

And that's just fine in this release, because the previously basic Bing functionality in v1 has been significantly updated with new features and functionality including:

Local Scout. Available as a standalone app of sorts (it's pinned to the Start screen) or via the Bing app's new App Bar, Local Scout is a location-aware "neighborhood guide," in Microsoft's words. Local Scout may be the single most useful feature in Windows Phone 7.5, and it's a great example of how this platform's integrated approach really works for real people out and about in the real world. Local Scout is as simple as it is useful: Just tap the Scout button in Bing (or the Local Scout app on the Start screen) and it will analyze your location and come back with lists of the best restaurants, sights, shopping, and other places that are near your actual location. Whether you're in an unfamiliar place or simply want to rediscover your home town with fresh eyes, Local Scout just works.

Bing Vision. If you've used Google Goggles, you get Bing Vision: You can use the phone's camera to photograph an item, like a book, or a bar code, or text, and then Bing will search for that item and provide ways, when appropriate, to buy it online.

Bing Music. Also new in WP 7.5, the new Bing Music also resembles another previously existing third party service, this time Shazam. And like Shazam, it works easily enough: When you hear a song you like, on the radio, in a sports stadium, or whatever, tap the Search button on your phone and then the Music button in the Bing app bar. In my testing, Bing Music works very well, and the ability to buy or download found music via Zune is a nice touch. And while I'm not too thrilled by the copycat aspect of this, it's a nice thing to have on the phone.

Maps. The Bing Maps app has been dramatically upgraded in WP 7.5, adding more accurate location finding, auto map rotation while using directions (which you can toggle off if you don't like it), audible directions, which is quite handy, and an improved presentation. I've used Maps extensively on trips this summer and I've never once wished for a more full-featured (paid) option. It's really nice.

Background audio

In Windows Phone 7, only the built-in (Zune) music player could play audio in the background--i.e. while you're on the Start screen or using another app--which really limited the availability of useful third party apps like Audible and Pandora. Those developers that did release Windows Phone audio apps didn't offer a great experience since playback would stop if you (inadvertently or purposefully) left the app, say by tapping the Back or Start button on the handset.

In Windows Phone 7.5, third party audio apps can now continue working in the background too, and my hope is that this change will convince third parties--like Audible and Pandora--to jump on the Windows Phone bandwagon. And audio apps that do utilize this capability can now integrate with the Music + Videos hub and lock screen playback controls as well, so it's the full meal deal.

Live Tile and notification improvements

One of the big innovations in Windows Phone is that it uses live tiles instead of simple, static icons to represent apps on its Start screen. These tiles can communicate "live" information to the user, such as the number of pending emails or text messages, your next appointment, the album art from the most recently played music, a weather forecast, and so on.

In Windows Phone 7.5, live tiles have become even more expressive thanks to some new platform capabilities. For example, apps written expressly for WP 7.5 can let you pin information from within the app to the Start screen, allowing you to quickly access something particular. The improved email app (described below) uses this feature to let you pin a particular email folder to the Start screen. A travel app might let you pin information about your flight. (These pinned experiences are in addition to the general ability to pin the app itself to the Start screen.)

Tiles can of course include push notifications, so when you miss a call, the Phone tile will immediately update to reflect that. These, too, have been improved in WP 7.5, and third party apps can now use the built-in numerical notifications or their own, custom-made graphical notifications.

Multitasking

While Windows Phone 7 did support multitasking of the built-in Microsoft apps, the platform didn't provide this capability to third party apps until the "NoDo" update that arrived, in piecemeal fashion, over the first half of 2011. Now available broadly to all users as part of WP 7.5, the new multitasking experience provides a handy way to choose between running apps: Just hold down the Back button to access the new Task Switcher experience, which presents those running apps in a card-like view that's awfully reminiscent of the same UI in webOS. (Just sayin'.) Whatever, it works well.

Next: With hundreds of new features, what I've listed above only scratches the surface of the new features in Windows Phone 7.5. So in the next part of this review, I examine many of the other new features, in an app-by-app rundown of the changes I think are most interesting.