User blog comment:Dbx25/Call of Duty Black Ops is gonna suck../@comment-1717312-20100601204134

I would say...

CoD4: Introduced perks and all that good stuff.

WaW: ZOMBIES! Improved on CoD4. AND it was made by teh uber Treyarch!

MW2: Callsigns and emblems and new attachments and lots of new guns.