I travelled alone with my 3 year old on EasyJet l, and the PlanePal was wonderful. Unlike the bulky kids carry on case alternatives, it was light and slipped in my carry on bag. Not being a case also meant I could carry my hand luggage compatible stroller on board and stow in the overhead locker.
It took moments to inflate and he was super comfortable in his little baby business class flat bed!
The only negative is that I understand Emirates will not allow them to be used on board. If PlanePal could work with Emirates to allow them to be used it would be wonderful. But this is a fantastic product, and worth the money compared to cheaper alternatives.