I went to a few of the iseries at newbury and the first one at stoneleigh park, but haven't been for a few years. It all seemed to turn into a drunk-twat-fest (some people at the last one had beer sprayed on their PC's by drunk twats) and full of cliques, and if you weren't in one of the cliques, it was quite boring

Especially if you're not into one of the main competition games (like tf/cs/cod)
I'd consider going again, but it would have to be with a group of chilled laid back gamers who just wanna do a load of less competitive more coop type games.