This installment from Treyarch got the company talking, the game is lush and colorful compared to the older installments, but its inherent optimization problem makes it not very good.
The localization is good - but there are some gags in the dialogues - and even effects during the dialogues.
The gameplay remained unchanged but they added a bunch of weapons and a new move - the dolphin dive, but it is not particularly useful. Treyarch's specialty in gameplay is its cruelty - compared to WaW, it is weaker, but still tough, which is even pleasing to the eyes.
The plot is fresh and exciting. The characters are well developed, even bringing back the old ones from WaW. Multiplayer is the bomb! She is the best of all! It has the first echoes of Class 10 from BO2, the weapons behave as they should, the variety of maps and damn Nuketown, which wanders from part to another. There are enough modes, there is an ideal game currency called CODPoints. It's easy to earn, and these points are also needed to unlock weapons, modules, perks, skins, etc.
Zombies have developed well here - this is the last part with an excellent zombie mode, then in other parts the bullshit is fantastic, it develops the idea of WaW, and does it very well.
The music in the game is good - the same composer from WaW Sean Murray. It pleased with powerful rock and a mixture of orchestral playing like in WaW. The sounds are good, unlike the MW series, it is not as real and raw. And in BO the sounds hit the spot perfectly, you feel that it is metal rubbing against metal.
An excellent game - but with flaws and shortcomings. I won't say anything about the DLC.