I never had interest.
COD4 was an average game, and the only Call of Duty allowed to be called good; quite a fun shooter in small doses, but I prefer Battlefield and others. World at War was shit except for zombie mode. MW2 was ruined by perks and killstreaks, very shit. And Black Ops is a nice shit that doesn't smell so bad at the start, but its still shit, and you're still paying full-price for basically the exact same experiance you've gotten with every other COD game, except worse.
Activision just whored it out waaaaay too much. When RE5 was released, it was marked down for being too similar to RE4. Same with L4D2 > L4D. And yet when we get the same shit with COD for the 4th time, it gets its dick sucked by every reviewer?
'Tards