the average/not so impressive:
Torches are gone (yay), but are replaced by an equally dumb system (you can stab down metal gates with spears).
The optimisation isn't great but the graphics are nice and the game still looks decent enough on minimum.
Agents are a nice middle ground between the ludicrously OP fots Geisha and the tamer Empire/Napoleon flavours, but the AI still spams them like there's no tomorrow so they're about as annoying as ever.
AI cheating is less obvious than in Rome II but the game is still full of one province nations with 2 full stacks and enough left over for constant agent actions.
The AI is a little bit better than in previous games but still displays a borderline downs syndrome very special level of reactive intelligence.
And lastly,
the bad.
The faction rosters are absolutely terrible. There are not only not enough units in each roster, but not enough localised faction rosters either. The Picts and Irish use generic Norse rosters (why give them content when we can sell them content) while whatever powers manage to survive until turn 60 in England or Western Europe are either using cookie cutter WRE or Germanic sets of units. I have spent 20 hours beating down dozens of stacks of the same 4 units as the AI never seems to research anything better than levies.
The AI constantly razes or abandons settlements and resettling is prohibitively expensive, leaving vast amounts of the map barren.
The fertility penalties are ludicrous. It's a cold snap, not the apocalypse. By 430, every single province will have a -4 fertility rating meaning that the highest possible fertility rating will be 1. According to CA, the entire Northern Hemisphere lost 80% of its yield in 35 years. Mesopotamia and the Levant should never become meagre land.
Imperium is not only still a thing but is horribly implemented, leading to the player faction having -80 diplomacy penalties just for having research, even if they only have one province with no armies.
The AI will not accept peace ever, even if you have a doomstack sieging their last city. Client states will also attack you even if there is no motive and they have no hope of winning.
The multiplayer is unbalanced to the level that it is effectively unplayable in any serious way. Tagmata OP, attacking testudo doesn't even work and shieldwall glitching dominates melee. Cookie cutter 6 melee cav, 4 inf, 2 crossbow, 2 archer builds dominate with any decent faction.
CA will sell you the fixes to all this in $8 increments.