Eh, I had pet 'possums as a kid (found their mother hit on the road with four live babies on her back) and they bit me from time to time. It's just like a cat bite. I think rodent bites are the worst. Sharp little incisors like a chisel. Ouch:-(
Opposums aren't like many wild animals, though...they never actually get tame. I released those guys when they were big enough and they did great. I'd see one or find their tracks from time to time.