Get Medieval II instead! Here's a list of Empire's pros (+) and cons (-):
+Massive, 3 Theater World (although crippled by small # of provinces - France being one province for instance)
+Many different nations to choose from (most of them sharing the same bland, cookie cutter format albeit)
+Naval Battles
+Open Ended Campaign
+New features such as governments, recruiting via generals (you don't need to recruit via a settlement all the time), improved economic system, a technology tree like in Civ (although most of the techs seemed more appropriate for a game that starts in the 17th century), a surrender option, revolutions, and a nation can't enter your territories without asking for military access or declaring war
+Nice unit animations, though somewhat unrealistic (melee combat feels like a one-on-one only affair, with other troops just looking by)
-AI (Campaign and Battle)
-Bugs (Half finished on release and I'm being kind)
-Mostly the same units for each faction, specially with non DLC rosters (excluding Native Americans, Ottomans, and Marathas)
-Same ships for each navy
-The game doesn't look good as Medieval II if not set on the highest settings; buildings really look butt ugly if you ask me when compared to Medieval II buildings, clone armies return (which doesn't feel right for non Western factions), 2D sprites look god awful (from trees to units)
-the worst sieges in the history of Total War (ladders were replaced by a system of your soldiers becoming Spiderman wannabes)
-atrocious pathfinding (I in fact won a battle because the entire enemy army was trying to pass between two buildings and their units got stuck there

)
-the reinforcement system is a major step back from the Medieval II Kingdoms one (a nation can't have more than 20 units in the field, which means reinforcements can only enter if one or more of your units has been routed or destroyed)
-neat game features from previous games missing such as family trees, prisoners of war, the ability to type in any amount of money to spend during custom battle, missions, the option to loot or exterminate settlements, kings who can be assassinated, each settlement having its own tax rate (it's now each continent), etc
-cavalry are frustratingly weaker than they were historically
-unlimited ammo for artillery
-ugly and historically inaccurate looking Janissaries (non DLC)
-lack of variety in music
-no multiplayer chat lobby
-lack of immersion
-Doesn't feel polished (Wonder why)
On a side note there is currently no mod for Empire with the likes of Europa Barbarorum, Roma Surrectum, Rome: Total Realism, Broken Crescent, and Stainless Steel (Darthmod ain't as epic enough).
Even though Empire is in a better condition than it was when it was released, I find it almost impossible to play the game without a mod - and I was content with Medieval II vanilla for months on end.