For a new rider I always figure the horse should be at least 7 years old. If the child is young (10 or younger) the horse should be one foot in the grave the other on a banana peel
Your daughter is old enough and experienced enough to have a younger horse. Personally I think this horse is a bit old for her. She will gain more experience as the horse becomes more infirm and need more care, less riding. Then she will either lose interest or want a different horse.
I would look at a horse that has been ridden lots of hours but is in the 7-10 (+- 2 years) age range.
Just FYI make sure she gets more than 1 ride in on the horse and doesn't just go by looks when choosing her new equine love.