I liked the crusade management, but compared to kingdom management it was a bit disappointing. It didn't have the complexity, I enjoyed so much in Kingmaker.
One thing I really missed was more flavor and detail to conquered lands. Regional specializations, variety in resources, opportunities and challenges. Some unique features to each fort. That sort of thing. By Chapter 5, I pretty much didn't care about any of my generic fortresses, whereas in Kingmaker I enjoyed developing every settlement.
The HoM&M gameplay addition was nice, but otherwise it felt like a step back.
Owlcat also made some silly mapping mistakes that irked me. For example, Keeper's Canyon is correctly placed (at the confluence of West Sellen and the river flowing near Drezen) and described in Chapter Two when your army defeats a demon fort there.
In Chapter Three, however, it is suddenly located as a buildable fort just south of Drezen (where in Chapter Two was just some unnamed fort). It may seem unimportant, but to me it breaks immersion.
Also I can't remember how many times my armies conquered Tower of Yath at different parts of the map in Chapter Five. Four times maybe?