I don't rely on the rating system, since it really depends on the game; there are some M-rated games I enjoy, and other's I wouldn't want to touch. However, the rating system is there for a reason, and people should at least recognize that. It bothers me to no end that some parents ignore the rating system on games altogether.

In my opinion, the ratings serve as a decent benchmark to give a general idea of what the game will be like. Naturally, the game shouldn't be judged by the rating alone, but I don't think the rating should be ignored altogether either.