Your bass and percussion needs some tweaking. One of the low drums you are using is being played at a pitch much lower than the original sample, resulting in some unpleasant sounding rattle (You'll hear this in my music too, which is how I recognized it)
I also feel the percussion would sound much better with some sort of stereo separation. Right now its VERY center-channel. For example, listen to how Hans Zimmer uses his Taikos. VAST separation.
I know there are some free low drums /Taikos out there that would work better for you. I'd also advise a little bit of 'humanization' for your strings. Its tough to make a digital sample library sound like it isn't digital, but a bit of variation helps.
As to the song and structure, it feels like the first half of a song. Not to say it is too short, but it builds up and up, then kinda hovers there before ending. Again, this is an issue I have too, which is why I notice it so quickly.
When you ask for feedback, also try and include a bit of info about what sample libraries you use, what software you use and how you 'master' it all in the end. I'm not sure if you were looking for such a technical response, but that's the best I can do.
I do quite like the vocal work though. Its nice to hear 'real' voices instead of a string of vowels running together. :)