Just watched the GT Video Podcast for this game and from what I remember it got a 9.2 or 9.3 not sure. Well it said that the game is a good FPS but it fails to bring anything new to the Shooter experience but overall it's a very good FPS, specially Online since Campaign is rather short.
About CoD 4 and Halo 3. I think Halo 3 is a greater FPS (though CoD 4 is very good as well) cause it brings much more to the Online "experience". First of all you have Forge and Custom Games which is genious. I've never seen any other game bring anything greater than that even though Far Cry 2 does have a pretty good map editor. Custom Games is great, you can make your own game type on your own customized map. Lots of things can be done. Then online, it brings in DLCs, Double XP weekends, Griffball. So I think it's generally better than any others for it's variation not mentioning the graphics it has.