Experiences with Canon Refurbished Lenses?

I'm pretty well set on one of my next lens purchases being the Canon 28mm f/1.8 USM.  I'm into photography just as a hobby at the moment, so I'm on a pretty tight budget, and the $450 price tag is a little expensive.  I know from time to time I see Canon selling refurbished lenses at a pretty decent price, so my question is, has anyone had any experience with a Canon refurb lens?  Any issues with the IQ, build quality, longevity, etc?

Thanks!