Okay, a few first impressions:
Campaign: Erm... What the fuck? The most ridiculous plot, needlessly over complicated with a shift between past and future that really doesn't work. Apart from being able to slightly customise your load out before levels, it's the same old wooden characters and linear levels. A bit shit TBH so rather than trying to complete it, I gave up after a few levels. I'll eventually go back and finish it but its a very silly game indeed.
Multiplayer: hasn't 'gripped' me as quickly as previous titles as there are a few things that I don't like so much.
The good: I love the majority of the maps - a nice mixture of small and large levels. Still getting to know their layout but they seem pretty good to me. Killstreaks (or score streaks as they're now known) don't seem to dominate and hence ruin matches like they did in MW3. They're much better in team games and its nice to be rewarded for capturing bases rather than just killing. And the 'Ghost' perk won't work if you camp - result there.
The bad: easily the worst thing about the game is - predictably - the quick scopers. Not only is it enabled but its easier to do than ever - the fact that so many people do it IN THE FIRST DAY does not bode well. I tried to do it to see how easy it is - and its exceptionally easy to do. Utterly ridiculous and it could potentially ruin the whole game for me unless they get rid (or at the VERY least reduce) them. But they've obviously made a conscious decision to include it so it won't be fixed IMO. Just so annoying. Otherwise, I'm not sold on the overly complicated menus/challenges. Black Ops 1 nailed this but it's a big step backwards that won't be quite so annoying once I'm used to it. Shotguns also seem to have a ridiculously long range again.
There really aren't as many 'fixes' to the game as I had hoped, it's definitely more of the same. That's not a disaster as the good parts are very good but it's a bit of a blow to see a couple of absolute pet hates included in the final game.
Still - it's only been one evening and there is so much more to discover/unlock and once we learn the maps and what loadouts suit us, it'll feel much better.
I wouldn't give it any more than 7/10 on first impressions though. I don't think it's as good as Black Ops 1.