Believe it or not, he was the best he had ever looked (I've seen him 4 times in the last 3 years). He was really funny - at one point a helicopter flew circles over the Bowl, which was really annoying (thankfully it happened in between songs), and eventually Williams cracked this joke about "Helicopters... now, that would be a good soundtrack. I've always wondered, are they in the key of C or the key of B flat?"
So as you saw, there were four encores, so Williams actually returned five times (counting the final "I'm going to sleep" gesture). Each time he shuffled off the stage, he looked kind of crazy - I would describe it as funny, wacky, and definitely sprightly.
Oh yeah, something I forgot to mention... during Superman, the video screens showed a montage of Superman and Batman clips, from the Routh/Reeve/Bale/Clooney/Kilmer movies... it was very distracting, and it made the Batman movies look MUCH better than they actually were!