Alright Start...
I do not know of the song you are trying to cover. So I won't be commenting on that at all. But rather strictly on the music itself.
First off, you have wrong notes either in the piano or acoustic. Unless there is supposed to be random dissonance like I'm hearing.
Now, this needs to be expanded both vertically and horizontally. Way too simple in every way. First off, drums would really help a lot. The drums you do have are anemic. You need more stuff happening in them. And not only that but you need to improve their sound. EQ and compress bud. That always helps drums sound better.
Now, you need more instruments on top of more/better drums. More instruments will allow you to have more complex melodies and harmonies. And that is important. You also could create new variations of the same lines, to build complexity and yet still keep the original thought.
Another thing to help you out would be chords. Yes, the evil C-word. CHORDS! Something less than 1/8 of Newgrounders know anything about. Go look at some chord structures and progressions online. That would be a good start to building harmonies.
If you are not sure why this is all important, go listen to some of my acoustic tunes I have up. Mongolian Banjoman, Dancing Banjo Duet, and Acoustic Tune to name a few. Maybe they could help give you an idea as to what all I mean by this.
1/5 and 2/10 overall. There just really isn't anything to this at all.
I hope this review helped you. Good luck on your future projects bud.
-Gravey-
Sawdust 
