Although it doesn't do much new stuff, it does what it has very well.
Although I, personnally, am not big fan of RTS, I think that if you are you would definetly like this game. Along with the replayibility factor, the combat is also easy enough to learn so that you could start right away. The larger battles are also very exciting and definetly add to the value of this game.
The most exciting things are the campaigns. Historically accurate, and engaging in their habit, they feature several consecutive games, etventually leading to one giant battle.
You should defintely get this if you are a fan of RTS, but if you're not, rent if first.