I used to (I cancelled because there were better/cheaper options for me for capped Internet service)... I used wireless a ton, and as long as you don't go over your daily download limit, it's plenty fast to be able to use FaceTime. I did it numerous times on ours.
I would make sure he knows he has a download limit first, and if he doesn't tell him about the "Status Meter" (you can download it from their website) that tells you how much more you can download for that day.... But if he exceeds that limit, it's painfully slow, and there's no way you can even pull up a webpage much less FaceTime.
While we're on this topic, I was a beneficiary of a Class Action Lawsuit against HughesNet, where if I filed a claim (which I didn't), I could get 5 whole dollars because they falsely advertised their speeds and failed to tell people before contracts of the download limit. Oh well... I'm happy they are out of my life.
