Total War rides out again, in a big way.
As you can expect from the Medieval II engine, the game looks and sounds wonderful, so I won't expound to much on it.
The meat of the expansions lies in its new features, including the middle eastern crusade campaign, the English campaign, and the teutonic knight campaign.
While this sounds sparse, the scenarios are deep, rich, and fulfilling. Very few things top massing the army of Jerusalem to march to war. Also, with 110 new units, variety is truly the spice of this expansion. My only complaint is that the game doesn't introduce any really new unique mechanics, and although the new units are wonderful, they play like any other unit. Also, and this has always been a flaw with Total War, the AI is spotty at best, and when you're defending against a siege, you usually need to goad them into attacking. Aside from this standing flaw with the game, its great.
Not much really to say, its more of what I personally enjoy. But if you liked Medieval II, there is no reason for you to not also buy this. A worthy addition and another excellent expansion from Creative Assembly.