I'm about to accidentally derail this thread, and not in a intentional way. It's about to turn into a Battlefield 3 vs MW3 conversation sadly and for that i actually do apologize... it's not my intention but someone is going to disagree as per usual.
Before it comes to that though... if your an avid gamer or TRUE gamer.. just freaking get both and play what you want.
To me, this is where call of duty will automatically fail until it reverts back to the ways of Call of Duty 4....
Dedicated Servers. "But Clinpachi oh goodness there will be dedicated servers in MW3", automatically wrong for several reasons.
1) Modern Warfare 3 will feature dedicated servers for UNRANKED matches only.
If you want to level up, unlock or prestige, you will have to play on the matchmaking side of things only. Server admins will have the power to disallow or allow items on a server which seems nice on paper but every server you join will have different rules or red tape to cut through when just looking to play.... this really defeats the purpose. But hey i guess some people might like finding one good awesome server who allows them to use anything they want right out of the box, having the option to say "Screw leveling up, i play on xyz server which allows stuff anyways".
They also expanded yet again on killstreak rewards.............

Tactical Nuke guys... it's ok it's tactical.
So anotherwords hey screw teamwork lets just try to be a solo hero and have the most kills at the end of every round.
The next big mistake is "Call of Duty Elite" membership. 50$ a year extra for a premium membership where you get DLC content and map packs a little before everyone else?.... Extra rewards for leveling up because you are "premiere member"? Are you kidding me?
I know this sounds as coming off as really really hating on MW3, and hell it might be, i may still pick it up and give it a try... but there is just way too many things out of whack with this game...
I mean look at the freaking Mountain Dew gamer fuel BS.... you get more XP by entering codes through mountain dew... so not only are they promoting another product they are creating a dependency on soda to get you faster exp......
Do you people seriously plan on giving into this pure amount of ***?
Battlefield 3 DID feature some Dr.Pepper promotions... HOWEVER... all they do is give you a bottlecap code so you can unlock a few dogtag customizations (5 in total)... dog tags do NOT give you a freaking advantage... just purely cosmetic....
Where is the line anymore?
Battlefield 3 gave me something i haven't felt in a long time, a sense of teamwork... getting the goals done over kill counts and k/d... helping your team actually win is the above all goal. I once had 0 Kills, and 12 deaths... but got the MVP 1 ribbon (highest score in game period) and was obviously #1 on my team for the leader board. I got my *** handed to me the entire game but i was the ONLY one taking over the objectives (I needed flag attacker ribbons to get a medal).
Not to even mention different play styles with vehicle variety... which actually are huge in difference... it's not just GENERIC half *** simulation in the jets or helicopters for example... you actually feel like your playing ace combat in a jet... its an entirely different way to play all together.
I'll probably succumb to getting MW3 and play with a friend or two, but i will NEVER sit there and buy 245325329 cases of mountain dew just to get 45 minutes of extra freaking EXP..... And i'll be damned if you'll ever see me prestige... Hell i might be one of those people who take advantage of a dedicated server with all unlocks just so i can play casual and not care... (Because that sounds fair right?)
I've tried my best to not turn this into a rant or physical "he's hating on MW3" type of post... but there's just too much wrong... too... too much...
Feel free to quote bits and pieces and take what i said out of context in attempt to argue, not really going to get into it over this... simply not worth it. I already stated at the beginning of this post to just play both if your an avid gamer... and that i even might pick up a copy to play on very casual or for single player.
Overall... I'm already disappointed in this.