The weave of acoustic guitar and organs, cut through by electric guitar riffs, isn't unheard of, but it's beautiful. You can hear the influence of the prairie mixed in with some sunny California sensibility and a playfulness carrying over from being in a party band. Morby has a Bob Dylan quality in his voice (but more intelligible) and his arrangements sound like a folksier Kurt Vile.
The title track clocks in a little over nine minutes and earns most of it. A jazzy rhythm sections slinks along while Morby slowly sings “I don't know just where I'm going / ‘Cause I've never been,” and the smooth jazz vibes are given some teeth with the occasional fuzzed-out electric guitar solo. He lets the song vamp out for the last few minutes unchanged, though, and on repeated listens, you might be itching to cut it short.
For the most part, Harlem River is incredibly mellow. The most it ever picks up is on “Reign,” where the drums get chugging and he introduces some harmonica. Even then, it's not aggressive. Morby has a very delicate touch on all of these songs, never raising his voice, the volume or the tempo. It doesn't make for exciting listening, but damn is it lovely.