Great idea but needs work!
1. Misleading fees -- I used a sign-up code which was supposed to give me free membership -- they charged my credit card the sign-up fee anyway! The website gave me no warning about this whatsoever - it looked as though it worked. I called them about this and they refused to do anything about it.
2. Snotty customer service -- they are very defensive -- not a customer service oriented company.
3. They end up nickel and diming you. It's not that expensive, but it is annoying. For example, it may take you awhile to get out of a parking garage because the last guy didn't properly sign in to a garage with the car2go parking card. Or you may need to get gas. All these things (and others like them) take time and you end up paying for that time. Another example: if you misplace your card they charge you a $25 "RFID fee" - even though RFID costs about 10 cents.
I am going to give them more of a chance since they are new to Toronto and I still like the concept. But I don't trust them as a company... you need to be vigilant with them.