I played all Kings Bounty games in the old days. This is by far my favorite. Yes, the quests are mostly running back and forth, but its just a nice touch to play as the evil guy (Demon Princess). Only one quest was broken (Camilla did not finish), but it did not break anything and I was able to end the game. There were about 5 crashes in about 100 hours, which is quite good for such an old game running on Windows 10.
If you like Kings Bounty you will like this game. Its much longer, but it has interesting and funny stories and I love all the details in the world.
In the first half of the game you will switch units quite often. When dragons are introduced and you play as Demoness, there is not so much change anymore, since your blood Priestesses can sacrifice troups to generate as many red and green dragons as you want. Enjoy the black dragons as long as you can, there are not many in this game ;)
At the end my army consisted of Arch demons, both imps (fantastic archers and melee fighters!) and red and green dragons. I used all objects and skills that boosted leadership for demons, dragons and neutral, which led to highest moral for demons and almost highest for dragons. The imps fireballs were devastating, very lovely to watch :)

I highly enjoyed the game and recommend it to any Kings Bounty and old school turn based tactics fan. If you play Demoness, play one above normal, it gets too easy soon with the dragons otherwise.

There is a mod out there that completely overhauls the game. It deepens the tactics, BUT it does not feel like kings bounty at all anymore, so I quit after about 20 hours and played without the mod.

The only drawback for me was