Very little. I like to read or watch reviews to get an idea of how the gameplay turned out, usually before the games released, but I don't purchase games due to a high Metacritic score, or avoid them due t o a low one. If I watch gameplay videos and it interests me, I'll purchase the game regardless.

This day and age, 99% of all games have a 6/10-10/10, so the review system is flawed anyways. Too many journalists are afraid to give a game that's playable a 5/10 or less because most gamers have it in their head that anything below a 7/10 is a bad game since they go by grading systems from school. What's the point in having the lower 60% if you're never going use it? This is the reason that the 5/5 system is the best. With the 5/5 system, a 3/5 is your average good game,the score that most games should be getting.

This isn't school, video games aren't on a school board rating system.  In a video game there are fewer categories that are rated, where in school, you take 50 quesion tests where you can still miss 15 and pass. 

Professional aka bought reviews - no weight, I stopped reading them in mid 2000s. I always read user reviews.

I usually only use a review to 'confirm' a feeling I've had myself from watching gameplay videos and the like. If a review is in line with my previous thoughts I do what I plan to do with the game. If it's not, I'll go back to the videos and make up my mind from there.

I will only read reviews of games I'm not sure about anyway, no review will sway me if I already made up my mind one way or another.

Reviews are important but trailers help me decide more. If the trailer impresses, the actual game is likely to impress me. Word of mouth also helps alot.

After Bioshock Infinite, Last of Us and Red Dead Redemption got a 9,5 on Metacritic I stopped reading reviews. 9,5 = masterpiece, not a Call of Duty in the air, flawed AI or glitchfest. Western reviewers score games based on internet hype and amount of guns and emotions in the game. REAL games (mostly Japanese games) don't get higher than 8,5. Mostly because they're too difficult for modern gamers or have a learning curve.

Content of reviews matters to me a great deal. Unless it's a series/developer who have earned my trust, then I just don't have enough money to be buying things willy-nilly without reading a lot about the game first. Even that mantra isn't safe anymore (I'm looking at you, Insomniac).

Trailers are no use either. I'm actually surprised at people saying they are. I love watching a good trailer; but I'm never gonna make a decision to spend £40 or not based on a trailer made as part of a hype machine.

A good review will tell me a number of things about a game, such as: What I'll be spending most of my time doing; length of the title; what the controls are like; what the sound is like. A video review will let me judge on my own the graphics & presentation. Sure, a reviewer will probably offer in a lot of their own opinion in there too, but there's enough substance for me to draw my own opinions based on what they say.

My favourite type of reviews are those that say things like "If you like [x], you'll probably enjoy this". It's what made me take a tumble with the Atelier series because reviews saying it had good turn-based combat and an interesting narrative approach. Which isn't for ever reviewer, but worked really well for me.

The score at the end is the bit I don't really mind too much about. I won't lie and say that if I saw a game with a mid-50's Metacritic I wouldn't be influence; but if it was a title I was seriously thinking of buying, I'd delve into the review and see why they scored it that way.

So yeah. Kinda important, to be honest.

I've found reviews less important in recent years. I use a combination of my personal interest in a title, the actual text of reviews, user play-through feedback and pre launch features like Nintendo Directs and gameplay videos, and occasionally a demo.

Review scores are completely irrelevant to me, and I think the industry as a whole attaches far too much importance to them.

If I play a demo/beta and really like it, then that's going to be a much bigger factor for me than any review. Soul Sacrifice and Dynasty Warriors Next got mediocre reviews, but I loved the demos and bought them anyway. And really enjoyed them.

With reviews, the kind of game and the developers/publishers involved determine how much weight I put on them. With fighting games, I find that a lot of professional critics don't know what they fuck they're talking about half the time, so their impressions don't mean as much. If it's a genre I don't usually play much, though, then the reviews play a much more important role. Gameplay footage and word of mouth are also important.

When buying a brand new game that is an brand new IP i tend to look at every review to see what im getting and if its scoring on a consistent bases of 4s or 5s then ill more then likely pass till a price cut but if its a well know series i like i tend to buy it anyways no matter the reviews to at least try it.

I don't trust reviewers (Maybe Giantbomb a bit, yeah, those guys rules), so I tend to use my own criteria and jugde using info and trailers. Alternatively, the only time I've trusted reviewers is when a very bad looking game "surprises" the reviewers, such as the case with Deadly Premonition. I admit I would have never looked at that game if the reviewers certainly wouldn't have labeled it as a guilty pleasure, and damn proud I am for having purchased it.