Ive had mine for quite awhile and the only problem ive had with them is the driverside headlight fogs up in heavy rain, but unfogs in less than 5 mins. And the only reason it fogs up is user error... I apparently didnt "caulk" it enough, but meh it was a first try on a cheap pair.
Very happy with the results, I am thinking of modding my other set and doing some led lighting effects within the housing. Wouldnt that be badass?
And ive had no problems with "yellowing" or "crow's feet" on my lens's, they are super clear.
Although im not sure what a regular halogen bulb would do to the lens.
I am sporting hid retrofit bulbs which run a lot cooler than halogen bulbs.