I personally liked the Rome: Total War (which came free w/ preorder via steam) more than Empire. First off, Empire runs pretty badly, even though I have a decent system (9800GTX+ GPU, Phenom II X4 920 CPU, 4 GB RAM). The loadscreens are so long it makes you never EVER want to play a battle, especially small inconsequential ones. Then there are the bugs... Ew. I have come across around 5 instances of a bug I have nicknamed the 'toxic assets' bug. This bug makes it so an entire naval fleet is unusable. It does this by crashing the game to desktop every time you click on it. This basicly makes the fleet worthless AND a liability (click on it and crash, better hope you saved recently!) The bug persists through save-load as well, so simply restarting the game won't help.
Troop AI really seems to suck. I think they just took the AI from Rome: Total War and gave it guns with a firing arc. And don't even try playing a seige battle with a city with fortress or wall defenses. You are lucky if you can get your troops to fire down on the enemy (or up at the enemy) without them trying to path to them, usually via leaving the walls (and their nice defensable position) and using ropes to climb down off the walls. Unless you are VERY good in the field, it is best to just hit auto resolve EVERY TIME, since you will usually take less casualties, and almost always lose them in equal portions (such as 17% from each group as opposed to losing 17% of your groups which would be normal for player controlled battles) You can pull off some really great defenses, especially if the bugs fall in your favor in the towns with buildings and no walls.
Artillary are fun to use as soon as you get cannister shot, especially in narrow alley ways against horse charges...
I have gotten most of the way through one of the long campaigns (100 years) but got stuck at 81 years, since the toxic assets bug rendered my invasion fleet to take over America all but useless, and I don't want to complete it until the bug is fixed for good.
Overall, I wouldn't suggest buying it yet, especially not for $50. $30 would be a decent price IMO, since there is quite a bit of fun to be had, but also way to many bugs for a supposedly finished game. The general feeling, with all the bugginess seems to be closer to the beta of SoaSE: Entrenchment about 1.5 months before release.
At this point, if you want a Total War game, try some of its predecessors.