It's true that you can still get by in rock 'n' roll on the strength of a unique voice. But it helps if said voice has something interesting to work with.
On the first three records by Heartless Bastards, that wasn't always the case. The Mountain, from 2008, had some terrific songs about a breakup, and a few that got bogged down in a rut. But on the band's latest release, Arrow, every song has a powerful, almost magnetic melody.