Weapons take too long to level up and this is coming from someone who finished the Damascus grind in MW. Movement feels really clunky and TTK is way too high in regular modes. Impossible to see enemies in Hardcore as well given no name plates show up. Camo challenges are also a farce especially with the Launchers given they have no predictable firing pattern.
Zombies is fun but I'm not much of a PvE fan, only doing it for the camos.
Haven't played campaign.