Call of Duty 4 was where I made my beginnings, but I never look at anything as a franchise. To me, Call of Duty 4 is a great game, but that doesn't mean I like Call of Duty. I like certain songs by certain people, but that doesn't mean I like the genre.
When I played Call of Duty 4 for the first time, it was an above-average first person shooter in my mind. It had more realism than Counter Strike, more detail than Battlefield 2, and more choices than other first person shooters I enjoyed at the time. The story arc in singleplayer was interesting and immersive; and in multiplayer being able to kit myself out the way I wanted, with specializations of both the weapons I carried and the abilities I had gave me a great sense of purpose and uniqueness.
When I heard Treyarch was making Call of Duty 5, I decided to get it, especially since it had co-op (an ultimate defining feature in PC games). Sadly I was disappointed with that, as it was my introduction into World War II first person shooters and was sadly similar to all World War II games: it was about World War II.
Still in love with Call of Duty 4, and disappointed with Call of Duty 5, I set my sights on Modern Warfare 2. I was rather excited for it, until I discovered one of the first interview articles on the PC version in which one of the developers or whomever boldly claimed to screw PC gamers over. My disappointment far exceeded that towards Call of Duty 5, which was now suddenly not that bad a game.
Nevertheless, I decided to pick it up on launch day because of the promise of its "special co-op mode" that I figured me and a friend could enjoy. My tirade on Modern Warfare 2 is deep and extends for as long as the Grand Canyon, so I'll conclude that the only fun me and my friend had was breaking the game by making a mockery of it while playing it (for e.g., scooting on our asses in wounded mode trying to complete the challenges), and getting an .exe hack so we could use the console as the Gods of PC Gaming intended (should they exist so help my soul). Suffice to say Modern Warfare 2 was a console gamer's game; full of all the fun extras that came with Call of Duty 4, but with none of the appeal that PC games usually have towards creative and intelligent players.
With Call of Duty: Black Ops here now, I guess my view on Call of Duty is even more incomplete, but a friend of mine who picked it up said that while he had wanted to hate it even more than Modern Warfare 2, he's rather enjoying it. This makes me wonder if it really is an alright game and that I should get it; the suggestion being that it's a return to form with the console reactivated and multiplayer support being rather important to Treyarch--whose standing has increased considerably in my eyes since Modern Warfare 2. But as long as they bring back the map compiler, have maps that are still GTK Radiant compatible, and add modding capabilities back into the game, I'll be willing to declare it a great game...at least until I shoot Fidel Castro. That's going to be a pretty darned silly moment no matter what I try to think...