I also own the game and all this hate seems a little off, the game is really great and its starting to look as most of the people complaining(MOST) dont own the game. MP plays fine and theres no lag, the experience is great, the game is even more fun than its predecessor.
Aside from the dedicated servers Ive loved the way you get better each time you level up. Faster knife kills, faster reloads, faster climbing is really cool and it really shows the difference with lower classes. Its addicting and the game rewards you all the time, for killing someone thats on a kill streak it rewards you, for running, crouching or proning, for using grenades for using any perk you get rewarded. Also care packages are insanely fun.