To avoid going off-topic. Cache, +1:) especially about the expansion pack. I read a bit about the classes and experience, and I was surprised))
Regarding the shortcomings of the third game, it's probably the infamous imbalance, which has been written about extensively. Imbalance in both castles and heroes. Many criticize the fourth game for its blandness, saying that the ideas implemented in it were poorly executed. But, for example, the idea of heroes with special abilities originated in the third game, and it doesn't work very well (it's not balanced). There are heroes that you're glad to have, and there are those that you pray don't show up. Although, any hero will do for the Fortress, it's more a matter of skill, but still;)
This, as they say, is just my newbie opinion:):D

Барон "Vampires"
Отдай свои прошлые сны,
В сомненьях себя обрети,
В бешеном танце душа кружится!
Не думай, что будет потом,
Здесь и сейчас мы живем,
Стань хоть на миг сам собой, слышишь!