Used Fastrak at the short term lot last night and it was a Fail.
System had no record of my entry (yes, I used the Fastrak lane and the transponder beeped). No ticket on entry, which should have raised suspicion. I pushed the button for the ticket and nothing happend.
On exit the attendant said there was no record of my entry. After about 10 minutes she left me out after paying $2.
I've used it twice in the short term lot and both times took more than 15 minutes to exit. There is only one Fastrak lane and it was blocked by someone trying to pay cash or with an unusable credit card. Also, the transponder didn't work properly the second time I used it, causing a huge line to form behind me. This, like most everything implemented by the city of SF, can fairly be called a failure.