I have played the "sandbox" game a few times up to the mid-game where I've gone toe-to-toe with a few Empires.  Overall, the game has become much more fun than the betas and is certainly worth playing now.  I look forward to seeing how the game develops.

Here is some feedback on the experience so far:

(1) Magic system is still a tad boring.  I know people have beat this horse to death, but while it is fundamentally the same as MoM (which is good), I think it lacks the early and mid game random variation that made MoM so fun.  In MoM, the ability to find spells "in the wild" from time to time (even early on) added to the necessity to spend some time exploring.  I expect that developers will be working on this part, but I think whatever they come up with needs to have a sense of "the unexpected" in each game.  After all, that's what magic is *supposed* to have: an element of wonder and mystery.

(2) Quests seem too "vanilla."  Since quests are slated to get some love fairly soon, from developers and modders both, I won't comment on this further.

(3) I would like my opponents to be randomized, like in GC2.  That way, there is some surprise in who I meet.  On higher difficulty levels, MoM would add a random special ability (or two) to each opposing wizard to spice things up and improve gameplay variation.

(4) When in tactical combat, I was fooled for a while into thinking that the way to access special abilities was through the spell book icon near the unit's mana bar.  I was frustrated that this would never work.  It wasn't until I saw the unit actions bar that the light bulb went on.  Maybe special abilities could be accessed from the spell book too, just to lessen the learning curve?