Windows Store is exactly what it sounds like, an app store for Windows 8. And even in this Consumer Preview version of Windows 8, where we can access only free apps, it's pretty clear that Microsoft has answered the needs of customers and provided a great apps platform that will extend the capabilities of the OS well into the future.
Apple may have entered the app store field under duress--as you may recall, the company's original goal was to keep the iPhone a closed system--but once it did so, it did it right: The App Store for iPhone and iPad is now the model on which all other app stores are based. More important, perhaps, it's inconceivable that any company could launch a new computing platform without an app store and other supporting services. And in Windows 8, that app store is called Windows Store.
Apps make the platform, generally, and the devices, specially, that they run on more valuable. Of course, that's always been true: Windows applications like Office and Photoshop make Windows more valuable too. But with Windows 8, Microsoft is taking a subtly different approach where apps can also step in to make Windows broadly more capable thanks to its extensibility features. So a developer in the future could release, say, an online store app that extends the Windows 8 file picker with support for that service, providing Windows 8--and any app that runs within it--with this new capability. Yes, we'll see plenty of standalone apps on Windows 8, as we do with various mobile platforms. But we'll also see apps that do much more than that.
Regardless of the capabilities, all Metro-style apps that will be installed on Windows 8 will come through the Windows Store: Microsoft is not allowing users to install apps from other sources, such as the web, so that it can ensure that Metro-style apps are reliable, secure, perform well, and do what they say they will. And while a long list of all the relevant rules for Metro-style apps would be a more appropriate topic for, say, a book, several do stand out:
App types. Windows Store will support free, paid, and trial versions of paid apps. Trial versions can be time- or functionality-limited but must provide a reasonable approximation of the full app.
In-app. Apps can provide in-app purchases, which are optional paid features, as well as advertising that conforms to Microsoft's standards. Apps cannot simply be ads, and they cannot be a shell to a web site.
5 PCs and devices. Apps purchased from Windows Store must be licensed to run on 5 PCs and devices that are tied to a single Microsoft account.
No adult titles. No Apps with a rating over ESRB MATURE (or equivalent) are allowed.
One tile on the Start screen. If you've installed Office or Visual Studio on Windows 8, you know that they spews tiles all over your Start screen. Metro-style apps can install just one tile.
Privacy, security, reliability and performance. Metro-style apps must conform with strict guidelines regarding user privacy, security, reliability, and performance. For example, apps must perform the same on any PC/device type on supported platforms, must start up in 5 seconds or less, and must resume in 2 seconds or less.
In use, Windows Store utilizes a standard, Metro-style design, with a horizontal scrolling layout instead of a document-like vertical scrolling layout. The Windows Store home screen is divided into groups, and it supports semantic zoom for quickly moving from one end of the UI to the other.
Navigation is fairly obvious, with browser-like controls, an Explorer-like breadcrumb functionality for sub-screens, and so on. Windows Store logically arranges apps into several categories (Games, Social, Entertainment, and so on), most of which are further divided into sub-categories; for example, the Games category includes subcategories such as Action, Adventure, Arcade, and many others.
Windows Store supports three major sub-screen types: Category, List, and App, and each provides a unique landing page where you find out more information or, in the case of the first two, further filter the view. A List landing page, for example, is curated by Microsoft and designed to highlight or showcase certain types of apps.
An app landing page provides information about an individual app, including Install, Buy, and/or Try buttons and a Details page with system requirements, release notes, supported platforms (x86, x64, ARM), and other information.
Microsoft has designed Windows Store to be quite interactive. You can rate and review apps you've downloaded, mark reviews that are helpful or unhelpful, and report reviews.
Search works as it does elsewhere in the Metro environment, via the system-wide Search pane (WINKEY + Q), though in this app, we're provided with search suggestions and even curated recommendations
Windows Store also extends to the web in interesting ways. Developers can republish a Windows Store-looking version of their app listing on their own sites or otherwise link to their apps in the store so that users who click the link from Windows 8 will navigate directly to their app's landing page. This means that users can use search engines like Google or Bing to find apps, which I suspect will be quite common. And as an added bonus, app developers can add a special app switch button to the Internet Explorer 10 for Metro navigation bar, which will let users download or run the corresponding app.
As with app downloads, all app updating occurs from within Windows Store. The store will alert you when updates are available via a number on the app tile, and then again, subtly, via a message in the top right corner of the app. You can manually check for apps via Windows Store Settings if you disable the default behavior, which is to download updates in the background and then prompt the user to install.
Interestingly, app uninstall occurs from the Start screen (or All Apps or App Search views), not from Windows Store. To uninstall a Metro-style app, select it from one of these views and then click Uninstall from the app bar that appears.
There's a lot more coming in Windows Store--currently, we're treated only to free apps, not paid or trial apps--but it's clear even at this early stage that Microsoft has examined how other modern platforms work and used its experiences with the Windows Phone Marketplace to guide the experience here. This is one part of Windows 8 that already feels quite mature.