There was a problem with some of the R2s: they came unglued at the BB. Cervelo replaced a bunch of them under warranty, sometimes even for people who wern't the original purchaser (so I heard). Some got new R2s, some got R3s!! Cervelo's handling of this is one reason why I bought an R3.
I think that the pretty blue R2s were the ones affected, but if you are going to get an R2, you should do some research (cervelo has a lot of info on their web site) and make sure that the one you are buying is not one of the ones in the recall. If its not, it's a good bike. I think it looks better than the R3 myself.