I've had this lense nearly 2 years now, its done very minimal light work.
Without notice it started giving lense error on both nmy 7D & 5D bodies.
I sent it to Canon Australia where they diagnosed & told me of the focus diaphram needing replacement. I was shocked at such an expensive lense needing such repairs given the short time I owned it and minimal work it had done. After getting over the shock of it all I decided to pay the repair cost of $530. Within a few weeks afterwards they sent me a repair survey asking my opinion on Canons service, I was still so discussed that such an expensive lense had failed in the first place, and the cost of repair, that I refused to even answer there request. It has now been 6 months after the repair, I have used the lense twice since and it now has the same problem again.