I've used OpenTable.com a bunch of times, but I'm still 200 points (2 dines) short of redemming for a gift certificate.

I've only had one problem with them. That was when I changed a reservation time and I wasn't credited. OpenTable.com emailed me with a warning that I missed my reservation without telling them. They have a whole system built in to dispute that. I did the dispute, as I called the restaurant beforehand and told them I had to change the reservation to 45 min later. OpenTable.com reviewed my dispute, said it was okay and gave me the points for that dine.

Other than that one misunderstanding, I'm quite happy with them. ^
OpenTable.com seems to be in place at a bunch of the higher dollar restaurants in my area.

Steve