Once it got into that whole Angel Treasures arc it was kind of dumb. First, Ueki and Robert Hayden are the only two kids in the whole tournament that can use that shit, but literally almost every single opponent they fought in the Heaven arc had that shit, which means they had to also be angels. Lol retcon.
Also, what the fuck is up with the LoU version of Heaven? How does that shit work? Where do dead people go? Soul Society?
Then there were the fights where there was absolutely no way Ueki should have won, like that big fight with Robert where he JUST WOULD NOT STAY DOWN.
Despite that I loved the show.