Played through the tutorial and a few turns of a campaign. Some thoughts...
1. Some general UI angst. While much of the Total War experience remains intact, especially on the combat maps, there's enough little changes that are obtuse enough that I had a surprising amount of "new game" vexation trying to figure out what was what. It's possible this is just first day learning curve, but there's a niggling feeling there that the UI isn't as elegant or intuitive as one might've hoped.
2. Combat does resolve a bit too quickly. It's not as bad as Shogun 2, where units seemed to melt instantly against their foil inside that game's ludicrous rock/paper/scissors balancing, but it's considerably faster than Medieval 2, which I felt got the pace about right. I'd have been fine with slightly faster, but this is a LOT faster. It's not so bad that I can't live with it, but I'll miss those big, boiling melees that dragged on for what felt like hours. They gave real weight to the combat. I'll also say that javelins at least traverse their firing arc way too quickly. They feel more like ballista bolts. Blink and you'll miss the volley.
3. Unit placards are hideously stylized and way too large. They also don't show unit numbers, relying instead on a decreasing health bar that is tougher to track at a glance. Thankfully they can be turned off, but that robs you of some fairly vital information. I'd love to see these addressed in a mod or a patch so we can A) scale the size and placement of them and B) choose to replace the health bar with numerical info.
4. Campaign and battle maps are pretty enough, but most certainly not preview quality. I toyed with some settings to give myself what I thought would be my best bet...the game will auto-set you to settings you really shouldn't be on, and then scale you down without actually telling you, so I decided to manually tweak and settled on "very high" for most things, with medium shadows and ultra textures. It's reasonably handsome, but it's not anything special. Fortunately 90% of the combat takes place from an aerial view anyway as you move and re-align troops.
5. Holy shitballs there are a LOT of neutral factions. No grey armies this time, there's a motherfucking LOAD of neutral factions. Watching them speed by during the AI turns was boggling. There must be 100 of them. I've also heard there's something on the order of 700 unique units in the game, compared to 40 or so in Shogun 2, with huge variation between factions. Big thumbs up, although the turn length will probably trend towards "horrifying" in long campaigns.
6. Load times are nice and brisk, a huge improvement over Shogun 2's interminable waits.
7. Sound assets are nice. Music was a little underwhelming.
8. Family trees seem to have been streamlined out of the game, and like Shogun 2 generals are now a set of player determined level up rewards instead of a set of randomly/genetically determined traits ala Medieval 2. Some players might like this, I feel it robs the game of significant RPG and AAR potential, and leeches away a lot of character. Big thumbs down.
9. Seasons are now gone from the campaign map, as turns are now 1 year long instead of 3 months long. You miss the slight visual changes for winter, along with some of the interesting tactical/logistics concerns of winter, and you also end up with your characters aging 4x faster than previously...another blow to RP and storytelling.
10. City infrastructure has been made significantly more complex, at least from the Medieval 2 era, and more than mildly confusing. There also appears to be a political system in place which is equally confusing (and if reviews are to be trusted, more than a little janky).
11. The map seems a little more "gamey", with provinces larger, and routes between cities deliberately piped through mountainous chokepoints. Whether this is good or bad remains to be seen.
12. You can no longer recruit armies distinct from generals, so no more randomly roaming mini stacks. Whether this is good or bad remains to be seen. I'm leaning "slightly bad" as it's a little weird.
13. Your armies now have fanciful names, which is kind of fun. Not sure if you can give units fanciful names as well. I rather suspect not. Pity if so, as it would generate attachment to have a named unit get killed, as opposed to Random Dudebros #5.
14. AI is still pretty typical Total War...not too bright. It's not showing signs of disastrous/broken stupidity yet, like standing gormlessly at the bottom of a hill while I rain missiles on their defenseless heads. But there's still time.
Will write more as I play more, assuming I have something of value to add. So far so good, I'd say. There's definitely some disappointing elements here, but there's a lot to like too, and the game feels considerably less arcade and streamlined into oblivion than Shogun 2 did...at least to me. I like it considerably more than the forums gave me call to believe I would, although perhaps slightly less than my hopes for the title pre-release based on marketing hype. There's a good foundation here for iteration through patches, expansions and mods.