Adding guns does nothing for the core gameplay unless it's a groundbreaking gun like the Portal gun in Portal or the Gravity Gun in Half-Life 2. Gravity changes everything that defines a platformer, and completely changes the gameplay. Not to mention having small spherical levels on their own are a huge change to the platforming style. You have to understand that there are really only two components to a platforming game. Level design and gameplay. SMG is changing both of these in ways that haven't been done before.
Also, I agree that I would probably give Halo 3 a 9 or so on the multi-player, but I haven't played the single-player so again I don't feel comfortable giving a score to the game as a whole. However, if twesterm is basing his opinions on how revolutionary a game is as well as how good it is I can see his reasoning. Personally, I just review on how good a game is, but he's got a different review style than I do. He was pretty hard on Bioshock too if you remember. Bioshock is great but it's really just a dumbed down System Shock 2. That game I have beaten and would confidently review as such.
