I've listened to this song a LOT (one of my favorites) so i apologize for what's going to be an incredibly pedantic review...
You miss a chord change at :44 and 1:10. I noticed it happen a few more times throughout the song. It's a minor I think. VERY IMPORTANT. :P :P
The biggest thing to me though is that the original version is a bit slower. Compare both versions. Stevens takes time to really put emphasis on the words.
Last thing. Get your bro to sing his heart out. Those parts are the most emotionally intense parts of the song! Make the listener cry. >:D
Anyway... beautiful song, great cover.