I'm into the 40s in online multiplayer now, and I'm not exactly happy with it (I play it mostly because Halo is still unplayable).
--The hit detection in this game is wretched. Worse-off, it's inconsistent. It's an issue that has plagued CoD games forever, watching the killcam of someone not shooting you...to death. Watching the game show several hit markers on an enemy whose only visible body parts are the shoulder and head...then watching him live through it. It's all horrible, and it's made me realize that CoD needs a new engine badly. The engine they use was built on the foundation od the id tech 3 engine, which is 15 years old. We need something new, guys.
--The maps in this game are the worst of any CoD multiplayer I can recall playing. Sniping is basically impossible on ANY map, unless you like to be an auto-aim, quick-scope guy. The maps are horribly small, and on the rare occasion you play on a map of any decent size (say, Instinct), there is so much foliage and so many obstacles that you still can't really snipe, because the opposition has too much cover and too many ways to easily get to you. A lot of it is the increased speed of the game (from double-jumps and dashing) makes it easier to get run up on, but it's also just the horrid map selection.
--I don't care for the number of lost things. The perks almost all suck now, with only a few even on my radar for in-game use. We don't have the Claymore is gone, making sniping even tougher without that defense (same for the Shock Charge of BO2). Basically, it feels like Sledgehammer is requiring everyone to play a run-and-gun style, regardless of preference. Strategy is out the window, with the deciding fact now being auto-aim and a sugar high more than ever.
When I started this game, I was good with the campaign, thought it was pretty solid. I even didn't mind the multiplayer, and thought it a decent attempt. However, the more I play, the more I feel like this might be the last time I touch a Sledgehammer game (I've already written off Infinity Ward). I really just wish that console shooters would dump the aim assist trash they use, because it's illogical and only props up bad players (I used to play the first BO with it off, but the hit detection is so bad in AW that I tried and couldn't get anything to register). This game...it infuriates me with its inconsistency and design. I just hope that Treyarch can again save the day, because the Black Ops installments are the only ones which have been good since the first Modern Warfare.