Reddit reviews Rats: Practical, Accurate Advice from the Expert (Complete Care Made Easy)

They're super smart and depending on their personalities can be super cuddly or a bit more aloof, or somewhere in between. I've seen people liken them to tiny dogs which I would say isn't too far off. They're quite social and nocturnal and don't exactly do well alone, so get a pair if you can. :) I've only ever had males, so their potty habits are the only thing I can speak to. Our rats would poo outside the cage when we first got them, but now they'll run back and use their litter box if they have to go. As far as pee goes, they do tend to pee on things quite a bit. It's generally only a little bit, but still pee. We had all of our boys neutered and that has cut down quite a bit. :)

Edit: I found this book to be quite helpful before I bought them. The price is quite low so it may be something to consider if you're curious.