Yeah it doesn't. People who say it does are either just sheep following a crowd, or quite often they happened to try a beta version of it (those did suck, lacked drivers etc.) and believe the final build is exactly like that, which it isn't.
A common complaint is the fact is that it uses more resources, memory/space etc., than XP. Which is kind of a given though, it has more stuff so of course it will. If you have a low end system then yes, XP is probably a better option, it doesn't mean Vista sucks, it just means you need better hardware to run it properly.
All operating systems have legitimate reasons why they "suck", Vista just got more stick because 1. It's by Microsoft, and 2. It was rushed and it could've been a better product.