I don't have a critique of this on technical merits, and obviously, an initiative that helps all users better manage information is step forward. And this isn't a critique of Microsoft specifically, but the descriptive copy for it follows a trend that bugs me:
> View and download sample apps, learn best practices, and see how other app builders are using Project Siena to build visually stunning interactive apps today.
Why does everything have to be "visually stunning" these days? No, I don't mean in actuality, but described as such? A service that can build useful apps that improve our lives should be associated with adjectives like "powerful", "flexible", "intuitive"...And no, I don't endorse the use of adjectives in general, I'm just saying I wish copywriters, their managers, their product designers, etc. would not worry so much about "beauty" especially when "beautiful" is something that can be seen and should speak for itself.
I guess it's not the copywriters' fault as so much as just writing what the public likes to see...I wish the public would expand their concept of what good software is, how "beauty" is great, but not at all the primary requirement for the domain of something like the OP.
And of course Microsoft is not alone at fault. If anything, Apple probably inspired it, and who can blame Apple considering their success? Look at how their copy for a spreadsheet application:
http://www.apple.com/creativity-apps/mac/
> Numbers helps you make spreadsheets more insightful — and more beautiful. Drop your data into a stunning, Apple-designed template. Or start with a blank canvas. Add in some quick calculations. Then visualize the numbers with a dramatic interactive chart. Suddenly, you see what it all means. How beautiful is that?
(I'll be the first to admit, I do like having nice typography in my Terminal, though)