I've been underwhelmed by each COD game since COD4, so I've learnt not to highly anticipate them.
These are my initial thoughts based on the leaked information:
The campaign story is likely to be as extraordinarily ridiculous and plot-hole ridden as MW2's, making Infinity Ward the Michael Bay of video games. I will cut them some slack for that, though, because FPS games rarely have great plots. The most promising bit of information about the campaign is that it's set in several different locations, which should translate to a wide variety of vibrant multiplayer maps.
The multiplayer maps are supposed to be quite larger, in their attempt to gain the interest of Battlefield fans and retain the interest of COD gamers who may switch to Battlefield. I'm not a fan of large maps for 6v6 gametypes because they slow down the pace and hinder rushing. Other than that, I'm glad they're using Infinity Ward's superior engine and that the beastly MP5 from COD4 is returning.
Do you guys want non-killstreak vehicles like tanks to be featured in MW3? I think they detract from the best aspect of COD; fluid gun fights.