Just picked it up yesterday. Very nice!
It is very different than the first one in a lot of ways, but also has a lot of similarities.
You no longer have designated spots to build. You can build anywhere, buy using the builder guys, who can be killed, but you can make more builder guys.
The only problem I am having with this is the builder guys going behind a building, and then I can't find the sucker to have him build more buildings. But over all I like the new building system.
Rather then breaking it down to Rohan and Gondor vs Mordor and Isengard, it is broken down into Men, Elves, Dwarves, and you fight Isengard, Mordor and Goblins, so you have 6 armies to choose from now instead of 4.
I have only done some skirmishes to get used to the game. But there are skirmish, good campaign, evil campaign and war of the ring modes. I am not sure yet what war of the ring is, but it looks interesting.
Dwarves are fun. You seem to have the ability to command more troops than in the first game. I had about 150 axe throwing dwarves reigning hell down on some goblins. Good stuff.