I was happy with this lens mostly due to how sharp it is and the ability to perform in low light conditions. But Canon has soured my feelings with lackluster service.
I took the lens to Utah this spring and the 17-55 and my 7D were exposed to blowing sand. It was a brutal environment, but my 70-200 f4 IS and 60mm EF-S lenses did ok, even a borrowed 10-20mm Sigma survived. The 17-55 sucked so much dust that dark spots were visible in the lens and on my images. Also the zoom became quite stiff in one section with a feeling of grit. Uggh.
I sent it in to Irvine and they charged me $90 to clean it and it came back clean but still a sticky zoom. A bit of silicon spray helped the zoom work more smoothly. Then the front trim ring fell off the lens, but I remounted it with some 3M adhesive for mounting prints. Maybe bubble gum and bailing wire next time?
Last week while on a photo road trip the lens stopped working completely and I could hear a loose object rattling around inside. I lost the use of the lens for two more days of travel. Bummer.
I contacted Canon. They agreed to service the lens since it has been less than six months since the factory service. I explained that I have an important event to shoot on 9/19. I paid extra to get it to Irvine by 9/9. As of today (9/14) Canon has only just acknowledged that they even received the lens. Four business days to say you received the shipment???? No business worth it's salt can say that's timely.
The rep I spoke with knew I wanted the lens for the 9/19 event and thought it might happen. Instead they will only begin to think about working on it and won't ship for at least another week.
What could be a rave story about excellent Canon service is instead sour grapes of lousy business practices. No matter how good the gear can be, if the service dept. doesn't do their job, we photographers will find ourselves disappointed.