Statistically he is a juggernaut. The points, rebounds, assists...everything is impressive about him as a player (granted, this is a surface-level explanation that is not going to delve into discussing usage rate, etc.).
That being said, I would have been thrilled to have seen him stay in Cleveland. With all of this hoopla about how Michael would never have teamed up with Bird or Magic, etc., I think this is going to just barely taint whatever championships the Heat win. Plus he had it made in Cleveland - he really was their king. And I like team loyalty to boot. No biggie, though. He made his choice and will have to live with whatever consequences - good or bad -come out of it.