I think why (some) people get so angry with G4 is how often they seem to be (dramatically) lower than the average review score, and how often their review doesn't (really) justify the score a game is given. Looking at their reviews on Gamerankings:
The following games were given a score at least 10% lower than the average review score:
Boogie (-38%)
Spider Man (-35%)
Rygar: The Battle of Argus (-33%)
Mushroom Men: The Spore Wars (-33%)
Tales of Symphonia: Dawn of the New World (-30%)
Castlevania Judgment (-30%)
Sonic and the Secret Rings (-29%)
Tony Hawk's Downhill Jam (-29%)
Call of Duty 3 (-29%)
Rayman Raving Rabbids 2 (-28%)
The Sims 2: Pets (-27%)
Avatar: The Last Airbender (-23%)
Tamagotchi Party On! (-22%)
SpongeBob SquarePants: Creature from the Krusty Krab (-20%)
Battle of the Bands (-19%)
Mario Strikers Charged (-19%)
Carnival Games (-18%)
Obscure: The Aftermath (-16%)
Elebits (-15%)
Metal Slug Anthology (-13%)
Ninja Reflex (-12%)
Alien Syndrome (-11%)
Baroque (-10%)
Kororinpa: Marble Mania (-10%)
MySims (-10%)
The following games were given a score at least 10% higher than the average review score:
Big Brain Academy: Wii Degree (+10% )
Boom Blox (+15%)
No More Heroes (+17% )
Cooking Mama: Cook Off (+18%)
Now, personally I think that part of this is that X-Play are simply tough reviewers and (unlike some reviewers) they tend to use the whole grading scale rather than focus on the top 40% of the scale. At the same time, I think they really need to hire better reviewers who can actually come up with a reasonable justification on why they gave a game a particular score.
