They recently got a lot lighter, they were very heavy before that. The chin fits very narrow and if you have a wider face cuts you up next to the eyes when you take it on and off. Quality wise they seem disposable every 2 or 3 seasons.
Air cooled? I would think top end life would be very good.
For a kid I would probably go with a 4 stroke though just because the torque band is easier to manage.