I just watched The Spirit last night, and it was a great BD experience. It's a generally dark film, so the HD really makes up for anything that is lost in the dark gradients. The cinematography and sound were straight up excellent, although the story was nuts. I liked it a great deal. Definitely better in HD than SD.

Best Samuel L. Jackson film I have seen in a while.

M60x2, VP150, M22x2
Sennheiser HD-595
Onkyo TX-SR507, PS3 (40gb)