The problem is that any given reviewer wont "mesh" with what *YOU* like. Or what *I* like.
OTOH, I find that the aggregate consensus of several hundred reviewers actually gives me a really good idea of how good a movie is. That's not the same as saying it's a good indicator of what I'll like; there are some crappy movies that I like quite a lot. But if a film gets an 80% rating on Rotten Tomatoes, and it has a significant number of reviews (obscure films sometimes don't), I can be pretty much guaranteed that it will not be a waste of my time. Perhaps it won't become a favorite, but it will be reasonably well-written, well-acted, etc. In other words, it won't suck.
I do occasionally see movies with low ratings, but only when there's some other factor motivating me -- and I often walk out disappointed. I also occasionally see movies that I have no real interest in, but have high ratings (and which my wife wants to see) -- and I nearly always enjoy them anyway. There are exceptions both ways, but the RT rating is generally an excellent guide.