Wikipedia has a pretty good description of this game in the entry "Medieval II: Total War." The PC version was released in 2006, so this not a new game, and it has some shortcomings that seem to reflect an early design that was improved in later games. For example, when the game pops up a note on some historical development, like the invention of spectacles or gunpowder, the date is not shown, a rather strange omission for a game that is ostensibly based on real-world history. Medievel II even omits the display of the current year of play, such as "1234 AD," a standard feature of other games in the franchise (no doubt intended to maintain a link to real-world history). There is an option to set a time limit on battles, but the battle Window doesn't display the usual clock, ticking down to zero. Graphics are a bit rough and "cartoonish," compared to "Shogun 2," for example. And so on.
This game is fun to play, up to a point: the settings, buildings, costumes, weapons and so on are pretty close to their historical equivalents; the battles are (as usual in Total War) fierce and unpredictable. City-building offers many more options in Medieval II than do others in the franchise, with everything from brothels to cathedrals available to build for your citizens, each with different costs and benefits. You may use Merchants to collect valuable trade items, Spies to discover your enemy's capabilities, and Assassins to take out an enemy general or two.
Balance has always been the "Achilles' heel" of the Total War series, especially in the endgame of a campaign: once the player has developed a solid economy for his Empire, and a big standing army, how do you keep him from simply rolling over every remaining AI opponent, in a Final Conquest that is just too easy to be interesting?—The designers solved this problem in various ways for different games; in "Shogun 2," for example, you get the "Realm Divide" condition, where the remaining AI all turn on you at the same time.
In Medieval II, this problem is addressed by imposing a strict limit on the number of units of each type that a city can produce: four armored knights, for example, or ten longbowmen. The result of these limits is that, for example, if you made the mistake of recklessly generating lots of knights to eliminate some pesky brigands in your expanding realm, and most of those knights were killed off during the campaign, you're in real trouble when a major foe invades with a whole army full of knights. No matter if you have ten times the cash NOW that you had BACK THEN, you can't get any more knights: you'll just have to make do with whatever other units you can dig up.
In a game based on real-world history, a limitation like this just doesn't make sense. As a result this reviewer quickly lost interest in Medieval II.