I totally lost incentive and stop playing in the mid of Act3.
I will try to keep it short and in point form:
1) Leveling is way too slow.
2) Building structures almost means nothing.
3) Loots are confusing and don't make sense, ie, I looted a L18 sword when I was at L6.
4) Combats are not challenging. Make all units range and win 99% of all battles in first attempt.
5) Skill trees are not exciting and most of the skills are confusing.
6) Nothing to look forward to. Nothing to unlock, nothing to gain, nothing to improve...
7) Tactical planning does not exist. One hero group wins everything.
8) No time pressure. I can roam around the map for 100 turns to build up a huge army and the enemies will still be the same as I was at turn 1.
9) All creatures are friendly. I was never attacked once by roamers...
10) The UI needs some improvements... it is not very user friendly...