I'm far, far from being a "front end" coder. So I can't comment on if this produces good HTML. If however it allows me to get something up quickly without having to become a "front-end" coder, then it's going to be very useful for me.
That being said my experience is heavy on the forms portion of their styling, and there is an extraneous div.input wrapped around each element, but you'd often do something like that on your own anyhow.
Generally: Good Stuff