My hairstylist was thinking of making an app for her salon. I was just taking a "Build an App" class at the time, so I voluteered to help. This is actually the third iteration, which I built after getting involved with Rails Girls.
I used jQuery Mobile UI, and foud it okay - not great, but not terrible, like a lot of fairly heavy-duty frameworks. I also set up Compass/Sass, which made my life a lot easier.