I've seen quite a few people who were in peak physical condition, but never with legs like this! That speaks volumes to his dedication.

Dem quads!!

Are those popping blood vessels unhealthy or just ugly?

Both.  And American cyclist George Hincapie's are even worse. 

Actually, he’s suffering from an unsightly case of varicose veins, says Dr. Walter M. Whitehouse, Jr., a vascular surgeon and Medical Director of Restoration Vein Care in Ann Arbor, Mich. In Hincapie's case, it's likely caused by his hours and hours of sitting on his bike. Sitting or standing for long periods can put pressure on the veins and cause them to bulge.

“These are the ugliest varicose veins I’ve seen in awhile,” he says. “They are more severe than the typical patient. I’ve seen bigger, but these are just a huge mass that are clumped together.”

Varicose veins indicate veins are blocked or pressured and fail to function well enough to carry blood back to the heart. When that happens, vein walls stretch and people can end up with scary-looking legs like Hincapie’s that can ache, swell and cramp.  

http://bodyodd.nbcnews.com/_news/2011/07/08/7044159-what-is-wrong-with-this-tour-de-france-cyclists-leg

Sounds like it's a fixable condition. I still wonder why anyone would do this to themselves.