The rockworks 'rock' is great, very grippy and believable. The boulders are surrounded by gravel, good if you land on your feet, but not ideal for landing on your backside - we take a light boulder mat with us.
Depends how good you are. I don't remember there being much harder than 6A but as someone generally climbing around the 6C/7A level there was enough to keep me entertained for a few hours. It's a nice place in general, so you could take friends too. I think my girlfriend had as much fun sunbathing /reading her book there as I did climbing.