I've tried many 4x games over the years and have always felt that something was missing....until I've tried sorcerer king.  I only have about 20 hours into the game (and about 5-6 restarts trying out different things), but this game has a lot going for it.  For the first time in a while, I'm experiencing that "one more turn" feeling.  

Here are the things that I like better in this game than other 4xs:

• I care about my units.  I don't seem to have access to many types of units, and at first I thought that would be a problem, but it turns out that not switching unit types as often makes me more attached to them.  Their leveling and the ability to equip them helps tremendously as well.
• Related to the above, great focus on heroes.  In fact I would love to see more heroes.
• Limiting city spam.  Thank you!
• The world feels alive.  With interesting places and writing.  Exploration is actually fun (as opposed to some other 4x games where you just explore to find opponents and new city locations)
• Battles are tactical but don't feel overly or tedious
• Asymmetric factions prevents you from dominating everyone by midgame...I think, haven't gotten there yet
• City management is light.  Yes its a good thing. I find city management in most 4x to be pretty dull.
• Crafting and enchanting add another layer to improving your troops and collecting crafting materials makes battles and exploration more rewarding.

My suggestions so far (for later updates or expansions):

• More sovereigns, heroes, quests, crafting materials, ect... Lots more of everything!  
• Random events (kinda like those currently used when the sorcerer king communicates with you, but for other things, such as a new hero for hire)
• Instead of having a single sorcerer king with his lieutenants.  Have a host of different "villains" that you can pick when starting a game, just as you have a host of different sovereigns.  Each villain would play a bit differently and offer different challenges to the player.  This would be like selecting your opposing AI players in a typical 4x except that it would only be a single AI player and it would be asymmetric.
• Expanding on the above, you could even have multiple AI asymmetric opponents.

Overall, I just want to again say great job on a very enjoyable game that has brought 4xs back to life for me!