This was a hit in its native Japan, possibly because of its meditative style and pondering on the nature of things. It certainly isn't full of action (there's no really impressive action until about 3 quarters of the way through). A ponderous pace leaves a lot of room for atmospheric tension and some nice strolls through Kyoto, as well as a lot of ear-bashing conversations between characters. The actual assassination attempt is a bit of a let-down as well. Certainly this seems entirely aimed at the Japanese audience, with some supernatural elements (the man in the grass?) that are perhaps over the heads of Westerners. Still, it looks great and feels authentic. Just not much happens.
Review of Owls' Castle
