A Whole New Game
There are some new units, and they are useful since some of the originals that you may have come to rely on have been neutered somewhat. Let's just say the balance of powers was re-adjusted and now you have to figure out the adjustments. Examined in a vacuum, it's an awesome game. When compared to the original, it only looks familiar but plays completely differently. This can be good or bad depending on what you expect.
At first, I was irritated that things I had come to expect were not the same. Now, I just have to re-learn and treat it as a different game, although it is generally familiar in appearance. The scope of the game is still epic, and the ambition of the developers is still magnificent.
I can't say it breaks as much new ground as the first game, but it's an expansion, right?
It has been tweaked and changed so much that it is really not the same game, but it has a big name franchise advantage, and it is a very good game. Since the game is a sequel, and not really examined in a vacuum, that makes it hard to evaluate. Some disappointment is due to not fulfilling expectations, but there can be some delights in finding new challenges. Since Strategy Gaming in particular is all about figuring out the little advantages, even though it was not my initial reaction, I have to lean toward the positive.