Must admit, I love Overlord, despite some problems I had with the second game (Better graphics, sure, but not as good a game as the first. It seems more like two or even three games all mashed together, sometimes - and not in a good way, either. I think several conflicting gameplay visions got in the way). I love the humour and I love that it's so different to anything else out there.
I'd also say that it IS an RPG, albeit a very odd one. It gives you real choices that have actual consequences in how the game plays out, enabling you to be the kind of character you want to be, which makes it definitely an RPG.
I'd like a longer game with less linearity for the third one. Dumping mounts is also a good plan, as while I liked the idea I don't think the implementation was very good. Also, the critters really need to be either levellable creatures or disposable cannon fodder, but not both. That was a strange and utterly pointless combination. And definitely no more 'kill or dominate 100 peasants in each town' stuff! Very, very, boring!
STORIES are both great, though. Just the gameplay that needs work.