Some of the bikes and/or docking stations do not register that you have returned the bike properly. This can cost you a lot ofoney for something that isn't your fault and there's not really any way to dispute it.
Any other costs are clearly stated (deposit, 30 min time limit).
Some of the bikes aren't in great condition. They are all very heavy. The older bikes have only three speeds. Hopefully you get a bike that has breaks that aren't worn out.
The concept is great but they are falling behind on the upkeep.