Exactly. What makes Doom so interesting is that he's basically just a human, albeit an incredibly intelligent and strong-willed one. He wasn't born with Super Powers, but a combination of scientific genius, magical prowess and utter ruthlessness allows Doom to stand and bang with the Gods themselves.
Also, while Doom is a vindictive, cruel, arrogant, manipulative bastard, he does have a(very)warped code of honour. If Doom gives his word, even to an enemy, he will not break it. Of course, Doom is one of the smartest men alive, and is perfectly capable of screwing people over while still keeping to the exact words of his oath if he doesn't respect them. He's also in the past refused to fight opponents who for some reason haven't had a Full Training Camp, since Doom believes such easy victories are meaningless and beneath him.
And while he rules Latveria with an iron fist(literally)he does care for his people in his own twisted way. For a tiny, land-locked Slavic country, they enjoy remarkable levels of education, health and security, as long as they obey Dooms laws. Crime is almost non-existent and anyone who attempts to attack Latverians is going to have to answer to the most dangerous man in the world. It's not only fear of Doom that keeps most Latverians loyal to him. Many take the view that while Doom is a monster, he's their monster.