No, I do not think that Stalin was a good leader. He was good at backroom political maneuvering. He was good at coercing people. But he was not a good leader.
Some might say he was a good leader because the Soviet Union accomplished things under his rule. It went from being a very backwards country to being a world power. This, they say, is evidence that Stalin must have been a good leader.
But the reality is that he was not. He was more like a good slavedriver, not a good leader. Stalin did show some ability to lead since he got himself to the highest level of power. He must have inspired some loyalty in those who helped him get there. However, once in power he was not a good leader. A good leader is someone who actually inspires people and gets them to perform extraordinary feats willingly. Stalin simply had massive powers of coercion and used those powers to force people to do things unwillingly. This is not, in my mind, the sign of someone who is truly a good leader.