It's Pretty Good
But not amazing.
The vocals were good, and I can see you were trying to make it sound authentic by making it sound rough.
The only real flaw this song has is the guitar, it's too quiet in comparison to the vocals and I found that I had to turn this song way up just to hear it. The only time it was sufficiently loud was during the guitar solo, and at the very end of the song.
This was a good attempt at an 1930's blues sound, it just needs a little technical work to be great.