Some people need to read IGN's ratings guide:
10.0 (Masterful)
No game is absolutely perfect, but 10s represent the pinnacle of gaming brilliance. It doesn't get any better than this, and products in this range are virtually flawless. This is like winning the lottery on your birthday. It takes a rare and special game to earn a 10 from IGN.
You can't really blame them for GTA4. Everybody fell into that trap. Gamespot, IGN, pretty much every reviewer on the face of the planet. They got moneyhatted. Don't hate them for one bad act.
And a piece of advice, if you're buying a game, don't just look at the pretty numbers. Read the actual review. If you can't be bothered, that's nobody's fault but your own. The review actually says what is good or bad about it and who it is recommended for.
Why should IGN give special treatment to the Wii? Because it's a casual console, the games should get higher ratings?
If you detest a genre and every game you have played in it and a game gets a 9.5, don't buy it. If you love a genre and have loved every game in it and love the series and it gets a 7/10, go buy it! The reviews don't tell you what to do, they just advise you. However, if there is another game which you love the genre and series of and it gets a 9.5, you would probably enjoy it more than the other game.
Oblivion, for example. I really like RPGs. Many people don't. It got a 9.2 on IGN, and loving RPGs I bought it and it is one of my favourite games of all time.
(Former) Lead Moderator and (Eternal) VGC Detective 
