@BatrozX:
The only thing that really disappointed me in this game was the music. Not that it is bad, but when you compare it to the music in Sonic 3 and Knuckles, Sonic 4 sounds incredibly average. I really expected much more from Jun Senoue.
@Darkstorm:
I only really find the mega drive era stuff catchy anyway, and he's only partially credited with 3 & K, so I've never really associated him with good music myself.
Senoue wasn't the main composer for Sonic 3 & Knuckles. It wasn't until 3D Blast on the Genesis and Sonic Adventure where he was the main guy behind the music for the Sonic games (not counting Crush 40's themes that later appeared).
Sonic 3's composers were Brad Buxer, Bobby Brooks, Darryl Ross, Geoff Grace, Doug Grigsby III, "Scirocco" and, of course, Michael Jackson. Howard Drossin composed Sonic & Knuckles' music. Jun Senoue was only part of the sound team, so he only provided little compared to the main driving force.
@Captain:
To be fair to IGN, each section (Sony, Nintendo, etc.) has completely different reviewers.
Which is really a stupid thing to do, as you get conflicting results, such as this.