What is your opinion about Heroes IV?

Well, I disagree about the genre; it was established by games much older than even the ancestor of the "Heroes" series, "King's Bounty" (if you're talking about the TBS genre). In the fourth installment, many things were ruined compared to the previous parts – that's undeniable, but many things were also added, and I think it would be simply foolish to abandon them in subsequent parts (but they did). For example, the ability to refuse a skill that is given in the witch's hut (a small detail, but it's nice).