I agree that the single player was better than MW2, although both campaigns are very good. I love that they brought back Special Ops, I honestly think that's the most FUN part in all of Call of Duty, especially playing through all ops on Veteran difficulty with a close friend. I did it, we yelled all over the place every other second (we're crazy as ****). Oh, man... Good times. When it comes to MP, seeing as I have 51 hours played in MW3 multiplayer, I have to like it in some way, right? I honestly never made it past level 30 in MW2 but I found myself being ranked top ~500 worldwide in Team Deathmatch in MW3 on the first day (played 12 hours straight with a couple of friends, wtf lol), and I really enjoyed it. Then again, by now people have leveled up higher than me as I have only played 2-3 games a day these past couple of days.
Maps, maps, maps... I would have to say the best ones, in my opinion, are
Hardhat,
Village,
Mission,
Dome and
Outpost (I like the snow there... it feels nice.
). I really like the way these maps are built, and that, on the maps I mentioned, there are alot of walls, doors, and stuff, so I find it very easy to just slaughter on those maps with my P90 using rapid fire and red dot sight (with the help of one of my fav perks:
Stalker) since I can aim down my sights while going around corners, doors etc., and people usually don't see that coming.
Favorite killstreak-rewards are definitely UAV (very important to keep track of your enemies!), Reaper, and the AC-130 or the Osprey Gunner. I only have the Osprey Gunner on some weapons though, the ones I really know I can get the kills necessary to call it in. Honestly, when it comes to the Reaper, I find it way more powerful and flexible than the AC-130. You can control and bend your missiles however you like, and if you're good with it you can even get the missiles to fly through open doors/windows into houses. And Attack Helicopters are really underrated, I've started using them sometimes aswell, they can easily get you 5-8 free kills if the enemy team is out and about, and not sitting in some corner somewhere. So I usually call that in and then I run asap into every building I can and just pick up kills so that they spawn outside for my chopper to deal with.
The weapon I use the most is probably the P90 (not probably, definitely) with Rapid Fire and Red Dot Sight, and for perks I use
Assassin Pro,
Stalker Pro, and
Sleight of Hand Pro -- Actually, I use these perks for every weapon except the sniper -- I got the Gold skin for it in 1-2 days. Apparently,
Village is the map (or so my friends are telling me, because I couldn't shut up about it in Skype) where I discovered that the bloody weapon is a "beast" (I stay true to that statement, if you use Rapid Fire). I have gold for the M4A1 aswell, which is the first weapon I leveled up. (Leveling up a weapon from 30 to 31 is a real bitch). Right now I'm enjoying the AK47 with silencer and Red Dot Sight, but I can't seem to choose between Silencer only or Silencer + Red Dot Sight... because If I have a bad game with it, I usually blame the silencer. But the sound with the silencer on is heaven, so I must use it! I would really like to level up the sniper, but as soon as some punk climbs to the top of the scoreboard in the other team I'm all like "The f*ck he think he is? Alright, I've had enough, ****'s going down. *switch to P90*". I always have to be at the top lol... Well, not really, but I refuse to have bad score; it's just a bad (or good...?) habit. In the Lobby, as soon as I see someone with a really high k/d ratio (2,5 and above), I try to hunt him down best I can, and play as carefully as I possibly can (while I run & gun ofc). It's pretty funny. Don't worry, though, I'm not a bitch or anything.
Make love, not war.
Also, there isn't much difference between MW2 and MW3 (same engine lulz), but it's very fun to play, and I like these maps better, for some reason. But I can definitely understand if some people prefer the MW2 maps. As with every other game, MW3 has awesome maps, and it has (imho) some bad maps.
Here's a screenshot of when my rank was at its prime... well, so to speak... number-wise.