Quoting a million user projects and 50,000 published apps (for both Windows and Windows Phone) over 14 months, here are some of the quoted improvements to this development system:
Windows Phone 8.1 Sideloading
When generating a Windows App Studio app, choose universal 8.1, turn on the slider for installable package, scan the certificate and the app, and check it out on your Windows Phone device. You can quickly test the new app you’ve created and share it with other App Studio members.
9 new languages added
Windows App Studio’s home page, How-To documentation, and app generation are now available in 9 additional languages including Chinese (simplified and traditional), English, French, German, Italian, Japanese, Korean, Portuguese, Russian, and Spanish. If you choose one of these 10 fully-supported languages for publication, the .appx package will include a localized resource file that will be used in the App Bar text, as well as the About Page. For additional language support, visit our How-To page to learn how to add your own resource files.
New Page Layouts
New app layouts are built specifically for PCs and tablets and allow you to assign multiple columns of data instead of the single pane that is usually used for Phone apps. The universal Windows apps you create in App Studio will be better optimized for phone, tablet, and PC.
We’ve also added a new Detail Layout optimized for text that uses a solid background and allows end users to change the font size to improve reading in apps. This layout will open a page in a modal-like window with better margins.
The Image Detail Layout will show your image at full-screen and will adapt to the landscape-portrait mode of your device. Also, the text associated with the image is now opaque to further enhance the look of your pictures.
Static Collections and Html
The data sources that allow for offline use (HTML and Static Collection DataSources) store data inside a C# class that can make it difficult to update the content once it has been generated. Now, all static resources are stored as json or html files in the Shared/Assets/Data folder, which allows for easier modification of generated code that displays content in the app.
Plus other improvements.
There are a number of helpful videos in terms of getting started with Windows App Studio Beta, including this one - start it and then go full-screen, etc:
For more helpful tips, videos and app examples, check out the Windows App Studio Beta home page.