I just spent some time with the Emperor's Edition for this free weekend, and came away fairly unimpressed with Rome 2. I was a huge fan of Rome 1, and I feel this game is inferior to it in almost every way.
1. Graphics: Rome 2 looks very good at high settings. The units on the battle map are fairly detailed, the terrain looks decent and the effects are nice. The campaign map also looks gorgeous.
2. The AI does a fairly good job on the battle maps. They attack in unison, send in their infantry to charge while their light/missile infantry support from behind, they actively send their cavalry around your main force and try to flank you. Overall, well done.
That's about all the good I have to say about Rome 2 though.
3. The UI during battles. It is completely useless. The game needs a simple, organized UI that lets you easily distinguish between units. The pictures on the unit cards are such that it makes it farily difficult to tell apart different units when clicking on their cards. Also, the current status(es) of the unit flash at the centre of each card in 1-2 second intervals. This means I need to wait up to 5-6 seconds just looking at a specific unit's card to see if they are under enemy missile fire, routing, or whatever. This is competely useless and unacceptable when previous TW games dealt with this much more efficiently.
Also, the lack of walls and siege equipment. WTF happenned there? One of the most fun battles you could have in Rome 1 was assaulting a huge city with a full army of light/heavy infantry, archers, cavalry, and most importantly, trebuchets. The onagers available in Rome 2 are fairly weak and just not as satisfying to use to wreak havoc in an enemy's city.
Another big issue is the campaign map province system, which makes it so that only the provincial capitals have large walls. All other settlements are minor, with to walls defending them. This makes it very easy to steamroll the majority of enemy settlements you encounter, and makes the overall campaign much too easy.
Speaking of the campaign map.... although it does look gorgeous now, much of its openness from previous TW games is gone. Italy especially feels just like a highway connecting 1 settlement to another. This is a problem because the game forces you on a linear path between settlements, rather than letting you do whatever you want.
Diplomacy is still an issue. The AI will propose stupid deals on a regular basis. For example, I would propose a mutually beneficial trade agreement and have it rejected. 5 turns later, I get an offer from that faction for a trade agreement, but they also want 4000 gold. Or I will almost destroy an enemy, and when they have 1 city left they request peace, but also want me to pay 10 000 gold to them for that peace... when I have a full army beside their last city and they have 5 units defending it.
The AI has some issues on the campaign map as well. There have been numerous times on the campaign map when I am holding a city wih a garrison of 20 units, and I am attacked by armies of 4-8 units, which are of course massacred by my forces. Thankfully, the AI works well on the battle maps.
Naval battles are an exercise in frustration and poorly implemented. You have little incentive to build actual navies, since when you order an army on water, they magically transform into transports. This is very frustrating when you have several enemy ports blockaded, only for them to send a random small force to attack one of your settlement behind the front lines... ♥♥♥♥ing seriously? Those transports will usually be a match for actual navy ships... making navies completely useless in the game.
Unit collision was a big problem in Empire/Napoleon, although I did not find it to be a big issue in Rome 2, despite it using the same engine. The formations are nowhere near as clear/fluid as in Rome 1, but unit-on-unit combat works fairly well. A unit of 60 cavalry charging into a unit of 80-120 light/missile infantry will make short work of them in a few seconds. However, combat between heavy infantry units is a bit of an issue. The units tend to lose formation and congregate into a blob, which kills the immersion and makes it frustrating to try to command units.
Lastly, the price. The game is a complete rip-off for $66.50 CAD, especially given the almost $100 of DLCs. The greek states should have been included in the base game, as should have blood/gore. Charging additional money for blood and gore is completely ♥♥♥♥ing ♥♥♥♥♥♥♥♥ (yes, it was for the rating. Well, ♥♥♥♥ your rating). Some DLCs are cool and worth it on their own, but it feels like there was basic content cut from the game just to be sold as DLC, which is unacceptable.
I held off buying Rome 2 for a long time, and after spending a weekend playing it, I refuse to pay CA for this game. Yes, it is quite a fun game, but it could have been so much more, and as a sequel, it ultimately just makes me want to go back and play Rome 1.
Well.... maybe I will buy it, but once it gets to under $15 CAD with all the DLCs. Otherwise, the game is simply not worth it, even at $16.50 + $20 for DLCs.
Edit: I purchased Rome: Total War Gold Edition and started a campaign in the original and in the Barbarian Invasion expansion. Comparing vanilla to vanilla, Rome 1 feels a lot more polished/better done and a lot more immersive. Very happy with the RTW Gold purchase.