Not bad... but not amazing either.
I couldn't bring myself to give too good of a score to this -- but, I didn't totally hate it either. :D
I'll try to listen to the song about ten times -- my review will sort of be a running commentary of my thoughts as I listened.
I really enjoyed the much different guitar that comes in at around :50 or a bit after that. But though the guitar sounded much better, it played far too loud, and drowned out all the other beautiful parts to the Halo theme music that made it so good -- the organ in the background sounded really nice, but it's so quiet...
This song does sort of sound like you took the Halo song, slowed it down a bit, and added in your own strings, guitar, and percussion to it, while lowering it all the same. The slower speed just sort of doesn't do it for me, I felt that the guitar sort of dominated the chorus (which is one of the coolest parts of the song -- but in the beginning, I give you credit for making them sound much cooler as a lower group).
I had some volume problems on my speakers -- it might be just mine, but it's a new computer, so it better not be. :D
Anyways, I noticed that when the guitar comes in, the volume of the guitar is three times as loud as the rest of the song -- the more I listened to the guitar piece, the more I felt it was grating against the rest of the ambivalence that this song has... it sort of takes away the relaxing atmosphere that you can get out of it.
Pretty much, it was a pretty good effort -- but, I'll be looking for more of your work in the future. G'luck!