I guess it depends on who's saying it. I learned long ago not to trust magazine reviews because those people get to see movies for free. I want my reviews to come from paying customers. Having said that, there's only a few people who have the same taste as me and it's only those people who's opinions I consider when it comes to movies.
Because going to the movies are pretty expensive these days I usually use reviews as an initial take if a movie is good or not. If I'm still not sure whether I'll be going yet, I'd ask any of my friends if they liked it or not. And more importantly, why they liked it or not.