Avoid the English dub (despite cool old UK trailer: http://youtu.be/CPkSinL4x9g) and go to the original-language version. Sonny Chiba vs Tomisaburo Wakayama and the evil spirits = must-see mayhem. Clear influence on KILL BILL too.
First 10 minutes are brilliant but definitely slumps along the way. Kenji Sawada (in some ways like the Japanese David Bowie) is always a treat, and Chiba looks cool as hell, so if you keep your expectations low, you will definitely have fun!