He's adorable!! Good luck with him. :D I'm a bit jealous, myself...I don't normally get lucky and find anything so fantastic, either. Although, I did once. He was an old (old, old, old) dumbo with a mismarked facial mask. Now, I'm not all about mostly white rats, just because I like colorful things, but he was kind of sweet (albeit jumpy, not held much, but was not aggressive at all, just nervous). He did well for me. I'm really sad to say he has passed on...and so soon...I knew he was old, though, and I don't regret getting his blood in my lines. So far, any keepers have turned out to be great personalities to have around. I hope your new guy does well for you, too! :)
And, to the person that released a captive bred rat...that was extremely, extremely irresponsible!! Never, ever do that again! The points Joanna made are very valid. It's detrimental, any way you look at it! Tsk tsk...bad person!