Not sure if this has been pointed out before, but my biggest issue right now is with champions.
1) When a champion levels up, the points gained are not enough to make the champion really powerful by late game. They just plain "get owned" by pretty much everything in the late game.
2) Champions don't really have much more health than any single unit you can train at your cities. That is a major problem because of 3.
3) When my level 9 champion with 30 health, 70 attack, and 30 defense fights a group of 10 bad guys with 150 attack and 32 defense, he swings, hits for around 25, then the stack retaliates and the champion is hit for 92 damage and is dead. Well, there went several hours of building up that champion for nothing. He couldn't even beat a single 'unit' that was trained at a city.
Now, the solution to this is simple: Let champions form groups. Then you can put all your champions in your army into one fighting group and they might be able to stand up to the other units.
Also, mounted units should be *much* harder for non-mounted units to hit. And, when they *do* hit, they should only hit for small amounts of damage because they will only get grazing blows. That is why mounted knights are so devastating against foot soldiers in battle.
I also have to agree with others that spells are exceedingly redundant and un-interesting. I'm worried Stardock is going to take a lot of heat from critics out there when they review the gold edition without updating to the Day-0 release.
Finally, while there are a lot of aspects of the new UI that I like, it almost feels like some of the stuff i want to use frequently has been buried in additional "layers" and I need to search for them now instead of having them right at my fingertips.
The champions issue is my biggest complaint, with spells my next biggest. When those two are addressed, then I think this will be a great and interesting game. However, I cannot really enjoy building up a champion when I know that if the champion engages in battle it will just mowed down. I also cannot really enjoy the spell aspect when they are pretty much all the same, not very powerful, and just plain un-interesting. On the other hand, the empire building and unit building are pretty good, but unless units can be combined into groups later and have their equipment updated, they will never be great.
Basically, I guess I just feel that the game is not yet finished. I know Stardock is planning on working on the game for the next year, but I almost feel like it should not have been released yet. I think it needs another 3-6 months of polish, at least, before I would consider it ready for release. I fell kind of sad for Stardock, because I can already see the critics' reviews ...they won't wait for 3-6 months for extra polish. They will judge the game based on it's initial release, and those reviews will stick around for years and keep people from playing the game and realizing that things have improved.