For me the the worst of Heroes 4 comes from it's ugly jelly-fish like animations. Most units simply look disgusting and way too cartoonish. Heroes 3 had the most realistic graphics in all of Heroes games even up to this point, while the latter games (from Heroes 5) started adopting this new BS like Japanese style animation where the colors are overused, and there are no logical symmetry or proportion in the model bodies, weapons, objects.Many have said that Heroes IV is a way worse than Heroes III. I recently saw a Youtube video about Heroes games, and this argument was brought up few times. That H4 was a bad game and that's why the NWC went bankrupt. But isn't it a mantra which everyone just repeat and don't really think about? Maybe all players are so accustomed to H3 that they didn't even want to try H4? Or maybe after a very good game which was H3, H4 was deemed to be mocked.
Other than the ugliness of units and the fact, that Heroes 4 adopted independent Hero "RPG" actions (which many people disliked instantly), the game is not bad.
Personally i disliked:
1) cartoonish animations
2) the 2,5 D battlefield
3) edited hitpoints of some units did not make sense.
4) Hero rpg abilities
These are major facts, the are also minor, but i am not in the mood to discuss this over again.