I found him predictable and boring not in comparison to other drummers (that's just a pissing contest that nobody is ever going to win, since it's so subjective) but in comparison with himself. Huh? Yeah, I know it sounds silly. But my complaint with seeing him and his band was really that the impression I took away was of calm, collected, constant and largely uninteresting chops. There was no "high point", no real impression that he was making any conscious decisions to structure what he has under his control. Watching Weckl is just that - a constant stream of Weckl.
For a great demo of what I'm talking about here, check out Vinnie on "Ten Summoner's Tales" by Sting. He keeps his blazing chops and fills up his sleeves most of the time, just plays interesting grooving stuff everywhere. Then, when he actually uses the blazing stuff he has available it has about ninety times more impact than if he just kept doing it constantly. Weckl bores me because he never paces himself well. There's nothing wrong with his tone, his groove, timing or technique. I just find him a bit on the tedious side as a musician, which is probably why his music has few fans beyond the drum community.