For last several years I have focused on the web technologies, starting with server-side technologies but lately client-side single-page style apps. So the h5c3js model is more suitable based my skillset. (Additionally, my knowledge of XAML is limited to WF serialization format.)
This model, which allows HTML-based native Windows 8 apps, is innovative in my opinion and I applaud the folks responsible for the language projection in Windows RT.
I was able to reuse this library in my HTML-based Windows Store app:
I can use CSS design tools that most web designers are familiar with.
Advances in CSS such as transitions, animations, transforms, gradients, SVG are at a point where one can accomplish most (if not all) of the things one can do in XAML.
I would like to hear about your experiences of course, but we have had some success in convincing customers that their web-based LOB apps can go native, and in the process, make their users more productive. Needless to say, if a web version of the app already exists, it is easier to get a h5c3js-based Windows 8 Store App going.
If the above reasons are not good enough, Kraig Brockschmidt’s (author of the OLE “bible”) delightful 800+ page book is a reason enough.
All that said, there are a few challenges one has to contend with.