I play VH/VH. I can confirm that the AI is much stricter about what it chooses to accept. Often youll have to give it an offer verging on generous for it to actually accept. Also be aware that unless you are considerably more powerful than an AI faction, it wont want anything to do with you so it can be very difficult to gain alliances until youre one of the top factions and even then the other top factions wont even consider it.

Also on VH/VH the AI is very quick to attack. You get almost no peace which is very frustrating if you want to try and focus on other aspects of your empire (like constructing those really expensive buildings youve always wanted but never had the extra cash for or trying to gain more than one or two crosses out of ten with the pope). The really annoying part though is that it leaves no room for unusual campaign strategies (like sending an army or two across the map to start up mini-empires where they land) because you have to always be ready for war on your borders which will generally come to you within ten turns regardless of how large your border armies are or how weak the aggressor is. Really the vast majority of my expansion has been retaliatory against factions that attacked me first. Only once or twice have i actually declared war on a faction of my own initiative.

The pope is also very harsh. I find it very difficult to have any real standing with the pope because everyone else just keeps attacking me and i keep losing standing because of it. Ive tried dumping my income into churches and priests (when i get a breather from constant war) but i find that i may only gain two or three crosses max out of it at which point another faction attacks me and i lose it all again.

As for battles, i find them very enjoyable. I can confirm that the AI doesnt get any obviously noticeable advantages. EVerything seems completely fair. I can also say that i take alot more casualties than i did in RTW. Gone are the days when i could get heroic victories time after time. I think ive only gotten one heroic victory so far. I was defending a settlement and at the end of the battle i was left with less than 10 men. In fact it seems that i take so many casualties that i now generally try to avoid battles that can be avoided where i dont have a considerable advantage because i dont want to spend the time and money on rebuilding my heavily depleted army. Especially when im seiging a settlement if the AI has more than a half stack of decent troops ill generally just wait it out because trying to replace all the casualties i take in the battle while continuing the offensive would be a logistical nightmare. Not to mention i really dont have the cash to rapidly replace casualties on a constant basis.

Thats the other major difference im finding. I dont have the droves of money that i had in Rome. In RTW once my empire was became medium sized i would be getting more money than i would know what to do with. Not so anymore. In fact i find myself desperate for more cash consistently every turn. I try every turn to begin construction of a building in every settlement that has an empty queue. In Rome i met this goal very easily but now i dont have nearly enough cash for that. Instead im trying to make the decision of blowing my entire income on a single really expensive building or spread it out a bit more on two or three other settlements (2 or 3 other settlements out of the 7 or 8 that have an empty build queue). Every turn i keep thinking that if i can take a few more settlements then the extra income will break me through my cash constraints and reach that position like in Rome where i didnt have to worry about money anymore but every time i expand i find my armies and other expenses expanding just as much and keep me in my relative poverty. I have to say that i really hate it but for however much i hate not having enough cash i wouldnt want the game to be any other way.