Looks are fairly important, but not all-important. Personality is all-important. Even if we both know the relationship is only sex, I just can't bring myself to be with a girl who's a *****. A good sense of humor, but not that annoying, suck-up, laugh at everything you say. And, for an actual relationship, I need a girl who actually gives a shit about me, a girl I can talk to when I'm not feeling good and she'll try to make me feel better. If I'm in a serious relationship, and what I mean by that is we actually love each other, she needs to show me she loves me and not just say it (and no, I'm not talking about just by giving me sex). Sex is good, and I do think it's necessary to at least have sex sometimes but it's not completely necesary. Hell, I'd be more than satisfied with once or twice a week. The one problem I have with a lack of sex is that I'm paranoid, which means that when a serious relationship lacks even so much as just occasional sex, it makes me feel like she hates having sex with me or finds me disgusting. I also need to be able to trust my girlfriend, because my paranoia makes me notice every little suspicious thing. If she doesn't act sneaky, doesn't give me a reason to be suspicious, I'll know I can trust her.
So, to sum it all up: Looks are good but not extremely important, good personality, good sense of humor, I do need sex but just occasional sex is fine by me, shows me her love rather than just saying it, and trustworthy.