User reviwes are useful, if the author presents the pros and cons for him, no matter if positive or negative. Such a review tells me if the game may be for me or not, a simple number does not.
After what some "professional" reviewers have written over the years, the percentages they give are highly suspect to me, too. I need a detailed review to decide if I like a game or not. Many reviews in magazines don't mention things I am interested in, too - like if I can save at any time, does it require a permanent online connection, is a DRM in place which can damage my system, at what resolution can it be played, do turns in TBS games take seconds, minutes or hours to complete, and so on.
The thing is, one needs to spend the time to make a survey on the net to get an informed opinion how a game does.