MP: Definitely an improvement from MW19. The sleekest, most grounded Treyarch MP ever which didn't personally appeal to me as much as the more arcade-style BO games of old.
Campaign: Really solid story with plenty of mysteries to solve.
Zombies: Major departure from the traditional Zombies experience with much less focus on the characters. Pretty fun but left me wanting more.

MP: Worst COD MP of all time. The maps are awful, gunplay is so jarring compared to most CODs, and everything graphically looks very washed out to the point that it detracts from the experience.
Campaign: Never finished.

MP: Very overhated MP experience. It build upon the foundation of BO3 nicely and the maps, pacing, and streaks felt like a return to form after IW's previous entry (Ghosts).
Zombies: Wasn't too confident in an Infinity Ward-led zombies mode, but it did not dissapoint. Differentiated itself enough from Treyarch's creation while also feeling familiar.
Campaign: Did not finish