I've been playing it for a few days. I never played the earlier version, so I'm climbing a steep learning curve. This game is complicated! But I think I'm finally getting my head wrapped around how the economy works. Some quick impressions:

The two features that really knock me out (so far) are the diplomacy and the ship builder. The galaxy feels very "alive" once you start interacting with other civilizations, and there are many ways to work diplomatic angles.

The ship builder is a blast. You can customize ships from a toolbox of parts. I spent most of last Sunday just getting lost in the ship builder.

On the downside, the overall graphic design is a bit cartoonish. The idea of the ship builder is great, but the results can look more like Lego toys than spaceships. My last space game was X3 which had beautiful ship and space graphics, so I guess I've been spoiled by the look of that game. It's a minor quibble though.

The other downside is no tactical battles. Everything is auto-calc'd, and then the game runs a little movie showing the 3D space battle. The developer is adamant about not including tactical battles. He says the human player can always find weaknesses in the AI and exploit it. I miss this feature regardless, but it does mean they can put all the programming effort into strategic AI for the galaxy map, and that does seem to be very strong.

Anyway, yeah... a fun game so far, and highly recommended if you're into pure (non-tactical) turn-based strategy games.

P.S. it would be great if MTW2 had this level of diplomatic interaction.