Why are people so amazed by this? Treyarch's last CoD game was CoD5 (World at War) and after the end credits of that game there was also a zombie mode that handled exactly the same with identical powerups and even music, the only noticeable difference is that with this mode you play as JFK instead of a regular soldier and it's set in the pentagon (well, the clothes and identities of the zombies are different, they looked like office workers in this video, they used to be nazis and even then the difference is purely cosmetic).
Let's not forget that in that game you were only given a single map for the zombies; if you wanted all 5 you had to buy the map packs or a the bundle for 2000 MS points (sorry for not knowing the conversion rate, but that's a lot of extra cash, not to mention that Black Ops is costing more from the get go because Kotick is a downright ****).
What I'm saying is if the zombie mode is what you care for then just buy CoD5 and save half the cost of the new game, even after the Map Packs (which you'd need to buy for CoD7 anyway).
EDIT: A few notes about the zombie modes both have; after wave 5 you begin to get your gimmicky, annoying zombies, like zombie dogs who are fast enough to give you a seizure among others. Keep in mind that these maps are made for 4-player co-op, not single player, yes a person can play the maps single player but the game spawns a LOT of zombies and without being able to share around the point cost of things (like blocked doors, locked closets, etc.), have multiple people checking/repairing entry points and the sheer number of enemies (the amount of enemies is made with 4 players in mind) and the fact that you don't have other players to revive you should you cock up. If you're a single player man you'll be disappointed.
I will admit though in CoD5 the game had such amazing mooding and atmosphere, truly some of the best I've ever seen.