Everyone is going to have a slightly different opinion on this subject but I'd say that generally looks are what attracts you to a person. Once you've gotten to know the person more and have an idea of their personality that's when things get important.
I have had crushes on guys before just because of their personality tho, and later on I began to find them physically attractive. I have also been very physically attracted to people who weren't the most friendly types and I soon realized that looks are just an initial superficial thing we notice about a person.
Yes, of course looks matter in a relationship. Yes, it matters to me also, but I give equal importance to personality also, and yes I do have my requirements, standards and both my physical standards and inner personality standards are very high and there is no compromise on either of them.
They truly don't matter much. I won't say they don't matter at all though. I like a persons personality so much more. I have liked so many people that I honestly thought I would never be attracted to, but when I got to know them as a person I really started to fall for them. I mean, my best friend is a really attractive guy, but I feel no attraction to him whatsoever. Like, none. I'm not just a looks person.
To a certain degree looks are important. They're what initially attracts you to a person but if said person doesn't have any substance to them and their personality is unattractive than their looks become irrelevant. In a way looks are a sidekick to personality.