What to improve...
Background voices are for the background, not to distort the foreground. I felt that I found myself paying more attention to the distorted "Uh's" and SFX. If you don't have the money for a PreAMP and a good MIC then I recommend getting an Audio Utility and making some balances. By balancing I mean lower the background noises and maybe add FX to them (panning, chorus's, reverbs, etc...) and the Lyrics are fine the way they are, thats a good volume for them. Rapping is hard but you will get better at it. I thought the lyrics were okay but that doesn't matter as much as the balancing does. The music was at the volume that the background FX should have been at so try increasing the volume with the music so that way it blends with the lyrics and that would make it flow together. So this is what you need to do...
Keep the rapping at the same level as is.
Increase the volume of the music.
Decrease the volume of the background fills and add FX to them.