The UX is the absolute most important thing. Anything that sacrifices the user experience just to make it easier to develop is a bad tool. It's a tool for the lazy.
Probably the biggest problem with PG is that it's frequently used with JQM, which in my opinion (after over a year of development with this combo) is slow. Mostly because it's browser compatibly goal is too broad.
I'd really like to see a mobile optimized version of twitter bootstrap for PG.