The whole point of the Jawbone is ease of lens changeability, so having a photochromic lens (from Transitions) kind of defeats that purpose. But if you plan on trail riding, winter commuting, or any scenario where your lighting environment changes rapidly over the course of the day, taking only a single pair of lenses with you is always worth it. These Oakley lenses are made by Transitions, who make some of the best photochromic treatments in the business. They adapt quickly to UV light (quicker in colder conditions), and have retained those properties over the several months that I've used them. Note that it takes direct UV rays to activate the color-changing particles in the lenses, so these are not optimized for driving. I got the Dark Grey lens option which goes perfectly clear for night use - no contrast, but the most versatile lens I own. If you're planning on a road ride and you expect to be under direct sunlight the entire day, neither of these photochromic lenses will get dark enough to give you protection for that kind of exposure - that's where the Jawbone interchangeability comes into play. I would suggest getting an Iridium lens like Black or Fire to keep on hand for those types of outings.
Otherwise, the Jawbone frame itself is awesome - oversized, and slightly aggressive. Hinges are smooth, and the Switchlock mechanism is simple to engage. An absolute must-have for the multi-sport, multi-environment athlete.