I had my first overage charge today, for a 50 minute ride. I went to run an errand crosstown during lunch, and even though I got the green light when I docked, I couldn't take another bike out upon completing my errand. Tried calling tech support then, but I could not get through at all. When I checked my trip status on my phone, I saw that my previous trip had not closed. I ended up walking a little bit to get to the bike I'd ridden on the first leg, and taking that back to work.
It'll cost me $2.50--I'm sure I could get it waived, but not sure that the time spent on the phone is worth it.
Aside from that though, the bikes have been great. I've taken them out on short errands and I love how much time they save me. I can pretty much have lunch anywhere in lower Manhattan now, instead of only at places that are within a 15 minute walk.