I was going to say, he gave them the benefit of the doubt a zillion times. Then they challenged HIM to a death match, so...not sure where this means Superman is a bully. The point of defeating them all but not killing them in the end was illustrating, "I have all this power, I could kill you, I could shape the world in my image and bend people to my will...but I choose not to, because it would be wrong." He was being merciful, because he thinks people should be merciful.
In any case, I think this was indeed one of the most enjoyable of this line and yes, it is a shame that it didn't sell more. I think I enjoyed it as much as Under the Red Hood. I remember some people saying they thought the animation looked shoddy in the few trailers that came out, but it ended up being quite fluid...