Alright. I've got a couple playthroughs under my belt now, and my first impressions and suggestions are below:

1. Champions need to be looked at. While part of my fun in MoM was to build up my champions there and go tearing about the countryside, here it's too easy to build them up. 
2. Leveling up traits, while I love them, are too powerful. They need to be looked at for terms of balance. Instead of +3 to a stat maybe +1 to a stat for a common trait. Rare leveling up traits show up too often. Maybe once every five levels. Rare traits should be RARE, something special.
3. Equipment needs a tweak, especially weapons which give the ability of "Maul". Maul, on champions or bears, is too powerful. The idea is fine, but there should be a big drawback to it. Perhaps since they are bezerking, they can only act every other round, or their defense gets a massive negative. The accuracy drop off is not steep enough. At most, one should get maybe 2-3 attacks. There is a rare trait which allows a character to attack 2 times in one turn: treat Maul as a rare ability.
4. At this point, there is no sense in imbuing a champion with magical ability. More on this in the Magic section.
5. Champions should not be immune to death. Immortal champions mean you just throw them into combat again and again. 
6. Diplomacy, at this point, is worthless. It was in E:WoM as well. There needs to be more options, and better AI for figuring out if they want treaties or not. As it is, the AI are just there to be taken over. Dynasties, in a way, will help this if implemented again. However, the AI is then just interested in marrying off kids. The AI should be interested in materials, rare metals, horses, wargs, treaties, demanding cities or tribute (though they do this already somewhat), marriage alliances, temporary alliances, asking for aid, and so on and so on. More options are never bad.
7. Speaking of diplomacy, each leader should have unique text for framing agreements/during diplomacy. Right now, they are all the same, and I just read it as the computer. Nothing.. unique there at all, which is sad.
8. Monster AI is bad still. It's better now, and I can see the territory they guard, but it's still needs some work.
9. Items should be rare, uncommon, and common as well. Getting the magic items made me squee with joy, but powerful items seemed really plentiful and easy to get. 
10. The tech trees look GREAT, but it takes too long to research any one thing, especially later down the road. By the time you get metal weapons, for example, you're going to have magic ones and armor from monster fights. There should be more techs, which take MUCH less to research. 
11. Buildings seem fine, but there aren't enough unique buildings (that I've seen SO FAR), and it doesn't seem to matter what I build. I just build one of everything and things seem to turn out ok. There's not any real choices that make a difference, or so it seems to me.
12. Units.. oh, units. I never bothered with them because by the time my units would be any "good", my champions were kicking so much butt already. And the old units I bought were swiftly made obsolete by new units, or by my champions who easily outleveled them.
13. Magic is... tricky. As it has been pointed out already, melee champions will outshine mage champions easily in the early to mid game... and sometimes into the later game too. 

I did see a few bugs, but those have been reported in detail already, so I won't go over them again.

Now, for suggestions, and these are based simply on my opinions so far.

1. More tech, with faster research times. This should be balanced, of course, in a way that seems to scale appropriately with the game overall.
2. Slower leveling for champions, especially after level 3-4 or so. 
3. Units stationed in cities should get experience. At one point in the game, I had broken through my enemies defenses and found... level one elite units, with which I mopped the floor. They were strong, but inexperienced. Think of it this way, idle guardsmen aren't really standing idle. They're training. Learning. Sharpening weapons. Whatever. Have Barracks and other special buildings give a bonus to this experience earned. 
4. Also, have techs and/or buildings where units start out with a certain amount of experience already, especially for the late game.
5. Have MONSTERS come up and initiate treaties with you, or ask for tribute, or give items or whatever. Have dragons and elementals demand that shards be set free of temples or something maybe, but in return they will serve you. 
6. Magic needs a boost. We should also be able to discover "new" spells like you discover items. That would be wonderful. I'm not sure how else to boost magic, but maybe if the champions are toned down melee wise, it might be balanced after that. Magic should be the ass kicking thing of the world, not bashing people with a hammer.
7. Bring back dynasties. Except make it more random. At the start of each game, determine how many children (behind the scenes) that each character can have, or if they are infertile. Don't just make it 'four' and call it good. Give the sovereign the ability to remarry after the spouse is dead, or divorce/kill them if they turn out to be infertile. I really thought it added a good dimension (if a bit shallow at the moment) to E:WoM. 
8. Champions should not be immortal. You have a system in place for this already with them taking wounds as they are defeated. Each successive defeat should add to the chance they die. It would be random, of course, but an unlucky shot could take a champion out in the first defeat, or a lucky one could survive through ten defeats. That way, the player would need to weigh the risks versus the rewards.
9. Heh. Give sovereigns scars too upon defeat. Heh.

That's all I have for the moment. I know I have more suggestions/observations, but I'm writing this at work and I don't have my notes with me.