Variety has an editorial up about the "ethically troubling" industry standard of exclusive reviews. The editorial specifically discusses IGN's GTA IV "exclusive," as the review site didn't get a "scoop" by finding some early copy of the game and posting a review, but by being given permission by Rockstar to break embargo. Every other outlet had to wait until this past Sunday.
The Variety writer states that he doesn't personally trust any review labeled "exclusive," pointing out "reviews are entirely subjective, so if a critic is being influenced inappropriately in any way, the whole thing is worthless even though we as readers can't prove there's anything 'wrong.'" The piece concludes by saying that any self-respecting publication with a GTA IV review should have run it the minute IGN released its review. It's a lovely thought, but the last thing any review outlet wants is a reputation with PR firms for breaking embargo. In a worst case scenario, if any of these outlets signed legally binding non-disclosure agreements for these reviews, they'd have to face the possibility of being sued.