This is a classic slow blues, with a "12/8" rhythm. The chords changes are the "Stormy Monday" ones, commonly heard in blues jams. In partiuclar listen to the chord changes in the last 4 bars of each chorus. The chords for the track in G are here.
Slow Blues in G
Slow Blues in A
Slow Blues in C
Slow Blues in D
Slow Blues in E
Slow Blues in F