The trouble with user reviews is that the majority of the time what you get is "worst ever" or "best game ever" without any actual critique. No talking about the aesthetics, the mechanics, the story, hardly anything of value. Saying something is the best or worst thing "ever" is not only not true, it's of literally no help whatsoever.
As such user reviews, except for the 1/10 that are actually well thought out (and rarer still, well written too) are generally unhelpful and have little merit. Critic reviews however I do appreciate, but always always always take them with a pinch of salt. A critic can (and in fact, must) look at a game objectively, without fanboyism, expectations or sweeping generalisations.
They will most of the time give a brief synopsis of the story, enough to know what the game's about without spoiling it, they will say how good the graphics and sound are, analyse mechanics, notice flaws and except for the odd Gamespot review that gets the reviewer fired for daring to give (was it Kane and Lynch?) a low score, generally they can be relied on to be impartial.
But even then, quite often I've thoroughly enjoyed games that received poor critic scores, hated successful ones and so on. The only gauge I trust is my own (and that perhaps of one or two game-playing friends) but a critic review helps me get an idea of what to expect, any glaring or obvious faults and so on.
"Too Human" is a stand out example of when a critic review was helpful. On paper, it's an action RPG in a unique setting, with classes, magic and lots of loot. Sounds great! But it was so lambasted by the media, it's flaws so glaring I gave it a massive berth. What would have been almost an ideal game for me on paper was so badly implemented with terrible mechanics which every reviewer noted, I avoided it based on that alone.