I find it very handy and convenient for quick jaunts across downtown when I'm in a hurry. Currently it works very well to get between the main office at work to one of our clients. Works out to be much faster than transit, and half or less the cost of a cab depending on traffic. Split the ride with a co-worker and it's as cheap as transit. And it's fun zipping through downtown in these tiny but punchy little cars through downtown!
I give 3 stars though because, although it has worked for me probably 85% of the time, there have been some hiccups including not being able to end a trip due to a jammed rear hatch door, as well as wireless connectivity issues when inside parking structures that prevent starting or ending trips. The help line is usually good to sort some of these issues out.
You also have to carefully study the parking locations on a map around your destination because in the event that your target parking lot is full, you'll need to locate another one in a hurry. You'll want the smart phone app for this.
Overall I like it a lot, but it can improve and it's not great for people who are not very familiar with their destination unless they're ok with the meter running as they figure it out. I hope it expands!