Hmm, to me the song seemed to lack structure. From what I could tell, it obviously has an intro, but the body of the song seems to be Brian Wilson'd, meaning that it's different sections strung together, which all sound very complete in their own right. However, unlike a Wilson peice, they don't lead into eachother, instead sounding like each section is seperate from the other. A simple lietmotif would help, but for a full effect, leading tones and chords can bridge the sections. An example of a song which seems to feel like what the song could be that comes to my mind is "On My Own" from the opera Les Miserables. Although it's vocal and fully orchestrated, it's a sad song that's comprised of different sections strung together, but makes effective use of chord progression to give it a direction.

Consistent use of arpeggios as the foundation of the song, although popular and common, is something I hate. A composer could use the pianist's left hand to contribute much more to the peice.

Finally, as Faw said about a lack of contrast, a simple way to acheive that would be to have the left hand drive with greater bass ranges.

Good points I noted :
The use of C-Sharp Diminished to resolve to F-Major was very nice. It stuck out greatly from Major and Minor chords, and was one of those leading chords I referred to earlier. Also useful would be things like Major-Minor 7ths, and although weakly, Dominant chords. Of course, I'm sure that's not really anything new to you.