[quote name='TimTucker']Now for the debate -- do I pull the trigger on this, or do I wait for Civ V?[/QUOTE]
I'd pull the trigger and then wait and see on the Civ 5 reviews. While a lot of the concepts stay similar from game to game in the series, there are usually many changes or improvements that can make individual games better or worse. Often whether you think a particular installment is better or worse depends on your particular play style.
In my case, I really liked Civ 2 and 4, but thought vanilla Civ 3 was a disappointment. Supposedly, the Civ 3 expansions addressed some of the stuff I didn't like about vanilla Civ 3, but I never went back and bought them to check it out. I finally picked up Civ 3 complete for $3 during a steam sale thinking I'd use it as a laptop game, but then I discovered my laptop would run Civ 4 so I never tried 3.
I'm hopeful for Civ 5, but the publishers have spent a lot of face time talking about the revamped combat and all the "streamlining" they've done so I'm concerned that is the focus of this installment (which is not my cup of tea).