1) It seems like you'll need to have some understanding of how web applications work to use the UI, and if that's the case you probably already know how to do trivial things quickly like creating submission forms.
2) Related to 2), browsers and the JS community are getting pretty good at doing things like components and modularity. Building apps should continue to get easier for developers.
3) It could work well for apps whose scope is contained in your feature scope, but when I need to do anything custom outside that scope I'll be out of luck.
Basically it comes down to whether the time that cloudboost saves me on web dev is going to be worth the extent of restriction on product. The lower that extent, the more it's worth it. Good luck to you guys.