I'm going to have to disagree with you there. SSM & PHG is filled with awesome humor, good action, fantastic music, great story, and a healthy dose of WTF. Other highlights are the crazy fashion guy and the businessman with knives. Yamada, the guy you're talking about, is easily the best part of the movie, to be for sure. The bathroom scene still sticks out in my mind as amazing Japanese cinema.
Gripes include underdevelopment of Samehada's best friend, underdevelopment of the three Yakuza goon brothers (Stinky, Bald Guy, and Inu-chan), and poor, poor lighting.
That, and Tadunobu Asano is a heartthrob.