Before he died in 2006, James "J Dilla" Yancey built an alternately immediate and arty sound — a mix of busy drumbeats, melodic keyboards and finely chopped samples — that made him Pharrell Williams' favorite beatmaker. This collection of unreleased material is uneven, tossing in undercooked instrumentals alongside tracks with MCs like Black Thought. But cuts such as "On Stilts" ride simple, effective hooks, and Yancey's taste for soundscapes comes out on "I Told Y'All," which splits the difference between DJ Shadow and Detroit techno.