Empire was totally unplayable on release, not just "buggy". The game as a whole felt really rushed and unfinished, but the release was awul. It was the first game I had to install Steam for and Steam at the time was horrendous, even trying to get the game to patch was a chore. The other games have been buggy and imbalanced on release but not as bad as Empire (like in Rome you could bribe massive armies for pathetic amounts of money and in Medieval 2 units with two handed weapons were unable to attack, plus other things).
In my opinion Shogun 2 was a great return to form after Empire and Napoleon, so I have high hopes for Rome 2. The only thing really concerning me right now is how far they will go with dlc. There was some good dlc in Shogun 2 I was happy to pay for like the Ikko Ikki and Otomo, but some of it like the FotS factions was just to make quick cash.