I just finished my first skirmish (played the texas map as the british) and thought I 'd share my opinion.
Start with graphics. This game is beautiful! My system isn't impressive, but it's OK and can run this on highest settings. I have a AMD 3200+, 1G PC3200 RAM, Geforce 6600GT 128 and ran at 1280x1024 with antialiasing on high with no problems. Load times were very quick too.
Gameplay. So much more than before. After my first game I can see that I've just started touching on the possibilities not just for strategies, but as to what all you can do with different units. The home city concept is great. I just finished my first skirmish and gained two levels and had to choose two new cards... very rpg like.
The physics of tearing down a building are just as you could imagine from the discussions. It really is nice to see.
For everyone complaining about the difficulty, the default selection for a skirmish is hard. I brought this down to moderate and won easily.
I also feel the interface is a bit much and couldn't find the current population limit (sure this is something I just don't know how to enable), but I can only assume this will change based on feedback. Not a deal breaker for me as I REALLY enjoyed my first skirmish... even though I had no idea what did what yet. Still so much to learn, see and do... and so much of the beloved attention to detail they always add to this series.. this game rocks.