My Honest Opinion...
I like how it starts out really smooth and free flowing, kinda happy...then u start to take a downturn and it just falls from there. Its kinda sudden and could have been transitioned into a little better i think. Then at the very end, it seems almost like its being rushed.
Now, Your beginning is excellent. Fits the description of the song well, in my opinion, very nice rhythm and flow. However, like Zadoo said, it needs work where it starts to take that downturn. It seems as though you just go into the minor keys without any real transition into it, then suddenly again you go back into a piano part. I have kinda mixed feelings about that, because the parts by theselves are fine, but they don't really fit the first half of the song, and thats what you should've been building upon. In my opinion, its almost like you started working on one song, then started work on another, and meshed them together.
Then about the ending: SLOW IT DOWN MAN!!! Seriously, its like it got rushed up to a million mph, then it crashes back into the ending, which is like the ending that fits the first half, and not the second. That last chord there at the end really better suits the first half of this song, and not that minor half.
So, in all my honesty, I have to give you......................5/10. Sorry.