Dom, my GPR, is amazing. He was cuddly as a baby but when he reached maturity he got a bit bitey and now I just leave him be. I give him lots of treats and talk to him all the time though. He's a big rat, very territorial and can be aggressive if you reach into his cage - which is of course his home. Other people have much richer experiences with their GPR's though, and can handle them and bring them out of their cages. They are I understand illegal to keep in the States, but are proving a popular pet in the UK