Why is this game the best? It features stunning gameplay and graphics and when you play split screen (I played with my brother) the game enhances it a lot.
its not just the gameplay that's amazing, the wide range of guns and maps that are mind-blowing. Yes you do have to pay for some expansion packs but all of them are well worth the money.
for an example, the Alcatraz zombie map. Most of you will not actually complete the map (I didn't) but its 100% better than green run etc.
I seriously recommend that you buy this game.