Why, what was broken in Shogun 2?
I'm not sure about 'broken', but the more I've played the more issues I've noticed:
Initial loading times make Civ V's lag look like, well, Civ I on a modern machine.
Vanilla naval warfare is terribly designed. Aside from the usual AI problems (and the AI really should not be programmed to sit its last ship in a corner when it's losing, since it takes too long to get to and deal with it), the maps are far too large (Empire/Napoleon-sized) for the number of ships involved with mostly short-ranged weapons, the dearth of ship options (battle speed or nothing, no facings to worry about) and the nature of the maps makes opportunities for tactical play very limited, so you end up with a large part of the game wasted on very pretty battles that are essentially autoclicking ... because the auto-resolve battle function also doesn't work. I was excited for the prospect of a more varied naval warfare game than the cannon-laden Empire allowed, but the execution in vanilla S2 is just dreadful. And while the difficulty in sinking ships is realistic, boarding action graphic sequences take much too long to play out, and again the battles are drawn out more than they should be even when they're a foregone conclusion (no more shooting the sails and causing surrender that way). Not broken so much as bad design.
AI problems throughout the main game. If anything they're worse than in older games. In fact I just started playing Rome - the game in the series I've tended to neglect, and it was only after having actually tactical battle experiences in that game than I went back to S2 and tried actually employing tactics rather than gathering a bigger army and rushing, since I'm used to either defending an AI all-in or launching one of my own. Though there's nothing you can do to stop the AI playing siege battles the same way every time. In the campaign the AI routinely does pointless or self-destructive things; in my most recent campaign the Hojo declared war on me in their turn after accepting a peace treaty in mine (they were losing badly but they were in the wrong direction since I needed to prepare for the Hattori). It still throws tiny stacks against you with no hope of winning. If a clan has one province left, and that's fully converted to another religion, the clan won't change religion (which aside from being poor strategically, means that if playing as the Ikko Ikki or Otomo you have a frustrating lack of control over who is going to adopt your religion - particularly the former since I've never seen a clan adopt Ikko that I remember).
Skirmish. This worked fine in older games in the series, but it seems to be a way of gently introducing new players to the series in the new one, and will punish you if you rely on it in larger engagements. I don't recall any of the older games having problems with pathing when sent to skirmish inside a castle, yet in this one they'll just run outside if there are any enemies inside. They seem to spook too early in the open field, so can be kept from ever firing (particularly with muskets) if attacked even by infantry. Using Velites I never have these issues, so I don't see why it would be intentional.
I don't know whether the musket line of fire issue in sieges is intentional or a bug - musket troops can only fire at troops manning the battlements, not those set behind (even slightly). This is actually reasonable in principle, but I think a similar issue in Empire was a bug, and it's not the way guns work in Fall of the Samurai. It's also not very reasonable that you can physically lob firebombs sufficiently high to sail over the wall and hit troops anywhere in the castle (as long as they're in range), but you can't fire in with a gun.
Also not sure about this one, but the lack of "Man of the Hour" (the Medieval name for the occasional general-generation when a general-less army wins a battle). The Shogun 2 encyclopedia mentions explicitly that in some cases a general will emerge if an army without one wins a battle, just as in the older games. I've never yet encountered it; it may just be genuinely rare (I've only ever had one defection, for instance), but I wonder if it's a feature that's meant to be there but that isn't implemented due to some bug.
Not broken, but a silly oversight - they create an in-game encyclopedia (at long last), and don't give it a typable search function?
Eh, I liked Rome a bit, but I'm just not that big of a fan of the time period, or really anyone in it (save Qart-ḥadašt). This is something like Shogun 2 that I'll probably get and briefly enjoy, but be unable to immerse myself in and have it just wasting space on my PC until I remove it. I was really hoping they'd just go into the Great War or go back and make an Empire II and do it some real justice this time.
Total War games don't really translate to conflicts with just two sides, with everyone allied with one or the other, except as a campaign pack. I'm not sure the Great War would be a very good fit, though I've thought myself that I'd like it in principle. I'd like the Crimea too, but a similar issue applies. I'd like Empire 2, since I think that is the most interesting time period Total War's touched on, and it will almost certainly be next after Rome 2, but I'd actually rather they followed the lead of Shogun and Shogun 2 and focused on some lesser-known, likely non-Western, conflicts for new time periods.
I liked the Maratha in Empire for that reason; unfortunately playing them loses a lot of the point of playing Empire - there's no need for naval warfare, there's no need to visit the European or American theatres of war, and diplomacy is irrelevant (except that for some reason the Austrians or other random factions will pop up from time to time to offer tech trades). If the Indian theatre returns in Empire 2, at the very least Persia should be a playable faction and there should be more interaction between India and the rest of the game world.
well excited about this about time, but if it cant get Total Realismed than it will probably be as disappointing as vanilla Rome, with ancient Egyptians fighting the many Romans on chariots from millennia before for "Flavour". although i will enjoy it anyway just for a shorter period of time.
Vini, Vidi, Vici.
I'd like to see some realism injected into the campaign scripting as well. At the very least, a random AI-led campaign should be able to generate something resembling the historical outcome from time to time. In Empire, for instance, the Persians will never defeat the Maratha. In Shogun 2, the Tokugawa are always the first clan to be destroyed unless the human is playing them, and it's very unlikely the Asai will ever stake a claim to the Shogunate (though in my current campaign the Ito - a minor clan - somehow ended up with 17 provinces and a Mighty army at one point); also the Realm Divide mechanic prevents anything like the historical Oda-Tokugawa alliance from lasting.