To answer your question: No. No he wasn't. He was a member of a rare breed of man known as "A Responsible Ruler". Vader threatened to blow up the city without so much as a "Duck and Cover" PSA if Lando didn't play along and make nicey with Fett and the storm troopers. He put the well being of his people over his personal feelings, like a good ruling body (I'm looking at you Washington). It's even mentioned that the original deal was to allow Han, Leia, Chewy, and the droids to be remanded to house arrest in cloud city, but Vader being the uncaring douche he is "altered the deal". So no. He wasn't a bad guy. Just a responsible person.