Some tips...
Not bad. You definitely could use an overall noise reduction. Also, and this is my biggest broblem. You definitely NEED the lead vocals panned in the center. In fact, If you had the lead vocals panned in the center, it would make this 99% better. It sounds like you used a tiny little microphone in a bathroom or a garage for reverb... which is incidentally a Really good technique considering what you had to work with. I'm guessing that the guitar is the only actual instument being played? Not bad, but the solo also needs to be more central in the mix. Maybe not in the center, I'd put it at about 33% right. It should be more in the center as well.
So to sum it up, overall excellent musicianship. Good singing, good playing, good everything. Except the mix. Hmm. Now that I listen again, it sound like maybe the piano is real too? I just might download and remaster this.
Good Job