First Impression - the most important one: What a lovely impression this couple makes .. I kinda hope their kid wins!
Composition: This is ok .. not fantastic wow type. Things to look at would be having a person on their left side with a good DOF type blur on them as well as those on their right side ... hard to do I know.
Subject: It met the challenge, and I think that you met the challenge well ... what is funny is you got the same comments I got ... "would like to see more of their faces"... hard to turn when you can't let them know you are photographing them without giving up the game :)
Technical (Colour and light): As you said ... light was not good but I think you did good with what you had.
To get a Ribbon?: It was a good solid photo, it just lacked the added wow that the ribbons got this time ... I think it is a very good shot though.
Summary:
Good shot, maximised what you had ... and going on to do better and better things ... it was a good try.
If you've got any questions about this critique, please feel free to contact me via the PM system.
Though one person isn't really singled out, the man appears to be in better focus than the woman. Overall, the lack of contrast in the background and the white area behind the man's head (area not burned?) are a bit distracting. (5)