I have flown Qatar on older planes in Y, 2 return trips to CDG and BRU. Found the service and comfort very good. My son and his partner also flew MEL to Georgia with QA in Y last November and said it was a great airline to fly with.
I flew Dohar to FRA on Dreamliner return last June in J. Excellent. It felt better inside as I did not get so dehydrated. Fantastic comfort as I had a single seat by window. Larger windows with dial the darkness controls. Good inflight entertainment.
Last Thursday I had a tour of Royal Brunei's new Dreamliner 787 which started flying Mel to Brunei leg on April 3rd. Two 180 cm blokes were giving the Y seats a real try out. They used the forward sliding seat function, (15cms) and found that additional recline was comfortable. They liked the lumbar support provided in the new design. they tried them out for about 15 mins and thought they were most comfortable. The dial window light selector intrrigued many people there too.
If anyone is very tall, row 43 has plenty of space for feet but is area near toilets and may become the chatty section of the plane. There is also special colour lighting which is supposed to minimise jet lag.
I am sure that your daughter will have a great trip. JoyV