I love my I/Os. The easy of changing lenses is so awesome.
I do have one grip with them though. A couple years ago it was very hot in the spring which caused a lot of sweating and slush to wet the goggles. It didn't cause any problems the first day. After skiing, I put them in the bag like normal. The next day they would completely fog up within 60 seconds of having them on. It never went away all day long. I ended up skiing with nothing for most of the day. After that I would have to completely disassemble the goggles and lay everything out on my desk overnight to have them be usable the next day. Again, this only happened during the hot, wet, spring weather.