First of all I'd like to say that you made wonderful stock choices and I think that both the horse and background fit each other amazingly!
Now moving on to the actual critique I have to say that I can't believe how well shaded this is. The lighting matches very well with the background.
I looked at the ribbon and the mane and tail and thought. Well the ribbon is blowing in the wind. The mane and tail show that there apparently is no wind. Even if it's the slightest breeze you should try to work on having it show in the mane and tail.
I think that the ripples look realistic and it's just great. I suggest for the reflection for it to go straight down from the horse... You may have a reason for it being slanted, but it seemed out of place for me.
I think that overall this was a great piece of art. I thought it was fantastic and showed your skills at manipulating and I congratulate you on making this wonderful piece.
I have a few little questions that made me curious. Does the red ribbon symbolize anything? How long did this piece take? What programs and tools did you use?