Play one COD you've played them all.
I can't agree more..
Meh, I thought 1 and 4 were alright. It just went very much downhill from there obviously. It also depends on what you expect from an FPS. CoD is not FPS the way I like it: I like more hectic, more lively games.
I expect running around killing everybody i see, because that's pretty much the only thing you do in FPS-games.. and that's why i don't like them.