The Photochromic sensitivity and range are really, really good. I purchased these right before my 9 day vacation at Powder Mountain, UT, and had no difficulty with the light. I didn't feel the need to squint at all on blue bird days, and my friends told me that my eyes were pretty difficult to see, since the lens had darkened so much. The photochromic feature was also good during cloudy/snowy days, and while my friends were switching or taking their goggles off for night skiing, mine stayed on, and did pretty well. The lens would not fare well in a direct comparison to 3 different lenses of high quality (bright, cloudy, night), but that's missing the point. These lenses are outstanding for changing weather conditions, and when you don't want to buy 2-3 different pairs of goggles.
The contrast and quality of the lens were pretty good, though not the best I've worn. I thought the quality of the lens and filtering of light was not as good as my iridium lenses from Oakley (my favorite to date). But there wasn't any noticeable lens imperfections such as waviness or spots.
I had two issues with them. First, the lenses seem to scratch very easily. I am all about buying quality, and protecting it as such, so I'm pretty delicate with cleaning and storage. For my Bolle's and Oakleys, it took me at least 15-20 ski days before I started seeing noticeable scratches, but I saw a scratch on the inside (from wiping) of the Julbos on my 2nd day... pretty frustrating. Second, I thought the fit closest to my temples was a bit weird. Hard to describe, but I feel like the pressure between the temple region (higher pressure) and my nose and forehead (lower pressure) was not consistent. This of course could be because I have a gigantic melon for a head.
All in all, I would buy them again, but I would definitely hope they improved the durability of the lenses.