The information in there is fantastic. Not only does it show every lift and run he took, but it also reports his speed, elevation, and total distance skied at any point during the day. (That graph at the bottom shows elevation over time. You can see our lengthy lunch in the middle there, plus the two runs we did at the end of the day near the bottom of the mountain.) You can replay the day to see where he was at any given moment.
If I get the chance, I'll strap one of these on me the next time I ski. It's nice to have a record of the day, and also to know how fast I ski. But I can't help finding something slightly creepy about the whole thing. Ah, it'll pass.