My first impressions:
Connection has been very good. I've had a couple of iffy moments and a couple of dropped games but for the majority of the time it's been good. Black Ops 2 has connection issues almost every game for me. Has removing theater done the trick?
The maps are big. Some maps it's difficult to find some people, especially in TDM where people just don't move. However, they seem pretty well designed and they look good. MW3 was all about SMGs where I think these maps cater more for other types of weapons too.
The guns themselves seem nice. Only used a few, really liking the Vector and I love the L115 sniper. It's no different, to me, to quick scoping in other CODs. What they've given is though is a fantastic scope to look through, really impressed by it.
The gamemodes are good as well. Some will LOVE Cranked. I enjoyed it but found the spawns got really messed up. I didn't feel like I was ever safe when I spawned. I spawned and instantly there was someone on top of me. A few times I took one step and I was dead. Not the biggest fan of Blitz as you can only get a maximum 8 points per round. I don't like rounds finishing like that in objective game modes.
The customisation is superb. The customise solider works great I feel and create a class is even better than Black Ops2 pick 10 system. It lets you be even more detailed with how you want your characters.
The character system, where you have 10 characters to rank up, instead of one character to rank up 10 times is one of the best ideas IW came out with. It's simple but incredibly ingenious. I'm going to rank two at once. If I'm in a party then I'll use the guy who started with CQC style perks, if I'm on, I'll rank up the guy who has Off The Grid unlocked straight away.
The squad points work well. As long as you can pay for it, you can buy it. If you want to use your favourite sniper straight away, go for it. I love this as opposed to waiting until level 50 to get the sniper I want. I feel I have more control, I'm not limited as it's me making the decisions of what I want, when I want (to an extent obviously).
The field orders is a great little innovation. Some are easy, some take a little camping. But it's an added bit of fun, something different.
MUTE ALL. Seriously, what a great feature. In game, choose who you want to mute. Mute anyone bar friends and that's it, you'll never hear the enemy again. I love this feature.
My only slight, and they are slight, annoyances is personal, I'm struggling to see people at times. I'm constantly running past people and not seeing them and they're right beside me in the killcam. I'm also struggling to see people in certain areas on maps. This might be my fault and nothing to do with the game but something I've noticed.