I just finished the available part of the campaign, here are my thoughts

First, this game is very well designed, I enjoyed the story full of interesting characters. Most mechanics works well, you can feel the vibe of older HoMM games. However, it is obliviously early access and you have to forgive some problems with the gameplay.

The biggest problem was with difficulty, or I should rather say, lack of it. I played on normal to feel the typical difficulty level, and I would say it is below easy mode in HoMM3. I have the biggest experience with this, so I will compare Olden Era to this. Opponents AI is utterly stupid, engage fights that are impossible to win for them. Additional one of the fractions have something like Town Portal spell build-in in every city, so you don't have to care about anything, opponents come - just spawn full army on his heads, and let heavens forgive him, because you're not gonna do this. That's kinda unbalanced and I'm not sure if it was good design decision.

Also magic is even more OP and broken than in HoMM3. With correct skills you can use spell book 3 times in each turn during the combat. Yes, I know what I've written. Opponent will lose more than half of his army before his first move. Or he will not survive to first move in some cases. Starting from some point in the campaign, you stop to care about what units you have, as most of the dmg you do on your own. I'm not sure if it is meant this way.

It also does not help that during fight AI does not use any tactic, just try to have higher initiative and jump to your archers/range units, that's all, nothing more. It looks like currently AI fight mechanic is scripted silly simple, instead of real logic and decision making.

Good point for choices that do matter later. That's a fresh part in the series, as campaigns was usual full liner in previous HoMM games. The art style is specific, first I was feeling it is too sugary, like Heartstone, not HoMM, but after some time I must admit I found it nice. Overall, except of weak AI that cannot use magic correctly, I rate this game high 😄, I will wait for Act II.