I would suggest that quantifying the value of the lives of prisoners is a pretty difficult wire to walk.
Do you swap one-for-one, or, as in the case, do you negotiate what would appear to be the best option to free your citizen?
Where would Obama have been if he had refused to do the deal, and the solder had been executed and the film placed on YouTube?
Impossible decisions have to be made, and time will tell if this was a correct one.