I know guys like this have skills but they rely on the harmonizer way too much. If they split-screened it and played the harmonies that'd be different, but the effect is just so tired and played, I wish the fad would just die already. Yes, Petrucci uses the effect, as do most players at some point, but there's truth to the "less is more" philosophy sometimes and this is definitely one of them.
It's damn impressive, though, as a guitarist (haha) myself it's one thing to hear the music and imagine how it's played but actually seeing JP, or anyone else, actually playing it and watching their fingers just makes have to change pants every time.
It's also one thing to cover something, but to imagine the effort it takes to actually write the stuff in the first place hurts my brains. I don't think us Dream Theater fans give the guys enough props for how much music they've actually written over their careers. It's quite mind-boggling.