It's possible I'm being too harsh, since I got the first game for cheaper than this expansion, but it seems pretty short for the money. The base game was a much better deal, however this is the first true expansion to the game. The other ones like Vietnam were just challenge maps.
There is only so much I can say about this game if you already played the original. If you haven't, you're better off just getting that game and playing it before seeing if you want to buy this add-on. It may go down in price in the mean time. It's pretty much the same gameplay as you see in the base game, just some new content. No major changes. It seemed to me quite a bit harder, but it may just be because I haven't played the game while.
If you played through magic and you really really need something new, then this is worth it. A nice feature is that you can have people who don't own this expansion join your games and play with you. I give real credit, and an extra star, for the developer to do that. However, if you're looking for something as long as the first game you'll just be disappointed. Single player only, I'd probably give it 3-3.5 stars.