It' worth the fee. Our mountain just bought one for the whole season and we were able to try it out last season. Really fun and everyone has a pretty good attitude. You ask any of the guys flipping how to flip... they will totally put you in the know. I'm pretty sure the age limit is less than 14 so you will be fine and your dad will have a ball.
I think you'll see a lot more of these bags popping up as permanent parts of the resort. If for some reason you can't get to this specific one there will be opportunities in the future. But... if you have the opp now... take it, lol.