I drove an R8 there a while back. It was good, but I wouldn't bother with it again. It's not very intimate. You arrive and park up with all the other hundreds of people doing it that day and get shuttle buses to a paddock. You go into a tent and watch a safety video, then sign on, at which point they try and sell you additional insurance and other extras like driving an Ariel Atom or being a passenger in a drifting Vauxhall VXR8 - which looked and sounded like the best thing going to be fair.
You can buy expensive chips and coffee while you wait - and there's a lot of waiting for both your drive and the safety drive they take you on as a passenger in an Octavia VRS beforehand - I think that was an extra, though, which was included in whatever voucher I had. It also included a passenger ride in an Atom, but I just left after the R8 as it was raining and my wife and child were having to wait around for me.
I would say look up plenty of reviews for the ones you're considering and see if there's any pictures. Also try and pick a day when there's going to be as few people as possible.