My old EF 70-210mm f4 lens (one of the 1st AF EF mount lenses converted directly from FD lenses in 1987) still works fine, though I don't use it anymore. My friend's 300/2.8L IS has been heavily used and professionally abused for a decade now, and it still works flawlessly. My 24-70L survived multiple drops (oops...) and other abuses....


So I guess Canon lenses (especially L lenses) are pretty reliable.