I for one think critics do a pretty good job taking in consideration most games these days.
There are just SO many games with SO many expectations and each is seen a dissapointment if it doesn't get 80+, 90+ etc.
Critics have so much to consider when writing reviews...things like platform its made for, other games of that type, is it moving the genre forward or just copying ideas by previous games...as well as each aspect fo the game like visuals, sound, gamplay, replay.
Just like everyone out there, I obviously disagree with some reviews. But I think about 75% of the time, most reviewers tend to "get it" when writing a review.
Unless the Reviewer is Hillary Goldstien over at IGN...he doesn't get it at all.