I think the game is fine as well. Never had any major problems since the first or second patch or so. As for the AI... Well, don't get me wrong, it's not super good or anything, but it's at the very least better than the previous games and equally bad at worst. Once thing in particular I've noticed is that the AI doesn't just stand dumbstruck while you're manoeuvering around it as much, and there's fewer stand-perpetually-in-one-spot-while-getting-showered-with-arrows moments (except for from ships - the AI really doesn't seem to understand how to deal with sea-to-land missiles, which can lead to some really stupid scenarios). During sieges, for example, if a unit is under fire, the AI will try shift units around to keep the point defended but move hurt units out kf harm's way. If possible (like during small town surges, where there is no wall) they might also attempt to charge the missile unit rather than just stand around like in previous games.. Oh, and walls actually help a little against arrows now, so you won't repeat silly scenarios from Shogun 2 where you could attack castles with mainly archers and kill every enemy without even setting foot in the keep. Well, okay - you won't get them
as much - unless you play Parthians, anyway.
So yeah. The AI still isn't great by any means, and you'll certainly start noticing patterns (and be able to take advantage of them) sooner or later, but I still think there's been an improvement. And I'm one of those who's always complained about how their AI has been getting worse over the years (and I would still complain about them focusing on shiny graphics over better AI if you'd give me the chance - that's still an unfortunate truth).
Maybe it's because I really like the setting or just because of the sheer variety of units, but R2 is certainly the most fun TW game I've played since Medieval 2 or maybe the first Rome. The thing k would complain the most about is the continuing lack of campaign events and filler. The whole faction thingy had promise (and I particularly like the concept of having to watch out for "Caesars" among your generals) but proved completely biteless (at least if you prefer playing non-Roman factions, which doesn't get more than one faction and one "others" - which doesn't count because it's dull - to begin with*. Maybe factions were better done with Romans, I haven't played them enough to know), which was sad.
Which was a complete waste of an opportunity to give the other factions some more flavour. Take the Gaul, Britons, and Germanians, where you can form those tribal confederations, which was unexpected and awesome. It would have been the perfect opportunity for factions - have each tribe start with just their own faction (and boring "others" one, I guess) and for each tribe that joins your confederacy you add another faction, providing some continual presence, purpose and gameplay even after you've eaten them all.