Call of Duty 4 was the first version I'd ever played, and up until that point the only FPS I'd played was Halo 2 and 3. Your description is right on though, and I also like how when you're playing team death match online you're team isn't always American or Russian or what have you. It's switched up. (I've only played on Xbox live, not the campaign). COD: WaW took some getting used to for me, but once I got into it I absolutely loved it too. 'Dome' is my favorite map...I always score major points on that one.
Anyways, I look forward to reading the rest of the series!