To take what Jeroth said about hating your friends to the next level, you really will come to HATE your friends. Unless you've got infinite patience and you're good at dealing with conflict, both internally and externally, you're gonna have more awful times than you will good times.
This also applies to your friend though. If they've got the right mindset and you've got the right mindset, it'll almost be perfect. There'll still be problems, but not terrible ones which is good. Me and a buddy of mine used to be roommates in a dorm. We worked well together. Then I moved in with some other friends because life prevented me and my original friend from living together. Those other friends and I were never on the same page about anything, to the point of us just not being friends anymore and them leaving the apartment behind while I was the only one in there for the summer. Thankfully the apartment was leased out by the room, but still.
It's just about being on the same page. I've lived better with people I've never met than I ever did with people I knew as friends, at least when it came to apartments.