Steam reviews are great source of information, many times it decided whether I will purchase it or not. If only Origin had such a feature.
Also, I'll post something else. Take a wild stab in the dark at the year Metacritic started to be flooded with whingers. Also take a note of the consistency of professional reviews compared with the ever changing standard of user reviews.

Reviews are more consistent when it comes to the professional reviewers (if there ever was such a thing?) but if you look at how badly ported some of the games were in the recent days, bugs, craches, DRM, that is more common today than it ever was before. Maybe it just points out the anger from the customers in that part? Assassin's Creed Unity could've been a great game if only they didn't force Uplay on us, as well as mobile apps for mini quests, many crashes, bugs.. Of course people are going to give a low mark even though below all of that there is a good game hiding.
I've read some of the reviews that are negative on Metacritic, and many of them have fair points that pretty much come down to technical issues and gameplay on the PC version. I haven't come across much trolls so far.
That's because most of the folks reviewing as users are just as bad at it, or incredibly biased.
I get people want to trash reviewers for their writing, and honestly they should because a majority of reviewers can't write a good review. But on the flipside, most users and entertainers forget the golden rule of subjectivity.
See, the biggest problem with games journalism is really the lack of rigor in the writing. There is no communication of ideas, few, if any, comparisons to genres, the use of slang and adjectives to describe everything without really talking about it. It is frankly a chore to sit through.
An example this is the opening Paragraph fro Joystiq's review by Alex Swilinski.
Dragon Age: Inquisition is an immense fantasy epic, a sprawling adventure across the many landscapes of Thedas, unapologetically mature in its exploration of politics and brazen in its combat. Inquisition is also developer BioWare's redemption song. It's everything that a sequel to Dragon Age: Origins should have been, and time will slip by as players enjoy the hundred hours of escapades it delivers.
Off the bat, it is nothing but praise, little substance as a lead in, throwing in a dig at Dragon Age II and at BioWare (conveying a specific narrative) and really telling us nothing of the experience. The words used, "unapologetically mature" "brazen in it's combat" are nothing more but buzz phrases. There is not analysis here, which is the problem.
That may be the first paragraph, let's go deeper.
But now here is the problem with users: they focus too much on the objective nature of things in a subjective medium. Basically, the only games that are "objectively bad" are things like Big Rigs or Ride to Hell, the truly broken experiences that never work or are half-assed as a result. Most fans tend to make bulletpoint lists off a rubric sheet to justify a score. You see it in big reviews too, almost in the motions checking off boxes until you hit an imaginary criteria that each game has to have.
Then throw in the axe-grinders, the guys who want to ****** on the game because of some actor in it, or some company made it. EA is the perfect example honestly, it gets hate for no ****** reason sometimes, and other times it's due to old grudges from 2002 that people need to get over already. People chastize Nintendo for being too "gimmicky" and pushing out the "same games", people tear down Ubisoft for pumping out sequels every year, or make fun of NIS America for their quirky pandering games. There are legit concerns in those practices, but the game itself should be separate from personal feelings of the practice.
Simply put, users are terrible reviewers because of a warped point of view and a magical quota they need to hit, while professionals need to learn how to simply write better, to provide a more meaningful, nuanced review. Even guys like Joe, who I don't consider a reviewer at all, need to learn this lesson if you ask me if they really want to be taken more seriously.