There are way better game's out there. Suggestions: Crysis, Modern warfare series, BF.
The graphics are manageable, I suppose. They're not all that impressive and can't compete with newer games. (Crysis eat's this game for breakfast.) With black ops fully maxed out on the computer there's not a noticeable difference to me compared to the consoles in HD, which I find odd.
The gameplay is the same as it's always been but now there's barely any stealth missions, maybe 1 or 2 and the stealth parts ends in about 5minutes and you're back to the run and gun gameplay. They added 2 new special weapons, the crossbow and the ballistic knife but they really weren't that much fun to me. The multiplayer is good when it comes to the customizing system. Reading combat records, creating emblems, buying weapons, etc. is really a good system for any MP game but everything else is broken. There's far less lag on the console versions, FAR less lag.
Campaign is really over the top and ridiculous in some parts. I felt like rambo throughout the whole game and I don't like that. Some people may but me personally liked the whole realistic feel. In the other call of duty games there were parts in the game that were actually possible. The story-line was pretty lame as well, and the ending was really stupid and non-climaxing.
So if you like call of duty games and you've played them since day 1, black ops will disappoint you. If you're new to the COD franchise, I'm sure you wont mind any of these problems because you have no expectations towards the game. Its decent but there are far better games out there.