Metal Gear Solid 4 has a review score of around 91%... I am NOT impressed!

[makingmusic476]

It's because Eurogamer and Edge gave it 8s. Both of which gave MGS3 8s as well.

Wait for more reviews. IGN NA, 1UP, etc. haven't reviewed it yet, and they all looked much more favorably upon MGS3.

Basically, the guys that didn't like past MGSes aren't liking MGS4.  That was completely expected.