How thematically ambitious is Bone Thugs’ fourth album, BTNHResurrection? Once strict pot devotees, the Cleveland posse now rap about Ecstasy, too. Deep they ain’t. But it’s never been about what BTNH have to say so much as how they say it, and the return of fifth member Flesh-n-Bone breathes new life into the group’s inimitable rapid-fire flow. The real star, though, is DJ U-Neek’s production team, which provides haunting beats and chilly guitar samples that should force Dr. Dre to get out his notepad.