I don't often get particularly enthusiastic about upcoming game releases, but I will confess to being highly intrigued by this--anyone else looking forward to it? Setting aside all the nifty new features and civs, the prospect of converting what is in my view very fundamentally a single-player game to multiplayer is an interesting one, particularly for a strict turn-based game, and Firaxis seems to have come up with a couple of interesting answers. The fact that they have so many variants alone makes the multiplayer aspect intriguing.
Plus, from what I've seen in the pre-release hype, they seem to be having a lot more fun with the civilization-specific unique units; most of the unique units from the original game just had a +1 to one of their stats, and usually not even a particularly interesting stat; only the impi are really truly unique, although there were a few other interesting units. But a lot of the upcoming civs seem to have some really radically different units (not to mention wickedly powerful-looking, though I've read that they're playing with the unit costs with unique units too).