Before purchasing EFS 17-55mm f/2.8 IS, I have gone through various other standard zoom lenses on crop sensor body. And I can say without hesitation that this lens lives up to my expectations in terms of image quality. In last three weeks of use, I have not noticed any flaw in optical quality. The IS paired with usable f/2.8 is capable of handling almost all situations. The USM enables fast and accurate AF. The FTM is very useful in focusing small subjects, when AF fails occasionally.
Unfortunately, my EFS 17-55mm f/2.8 IS is a DUST MAGNET. It has been sucking dust since the first week of INDOOR use. I put a UV filter, the moment I took it out of the box. However, it appears that the dust enters through barrel seal. Extending barrel design is not the limiting parameter for Canon to build a dust resistant lens. In overview of EF 24-105mm f/4L IS (extending barrel design), Canon confirms its “dust- and moisture-resistant construction” (http://www.usa.canon.com/consumer/controller?act=ModelInfoAct&fcategoryid=149&modelid=11924 ). To the best of my knowledge, Canon never confirmed dust resistant construction for EFS 17-55mm f/2.8 IS. Another interesting fact is that my Tamron 28-75mm f/2.8 (extending barrel design, $350) does not have a single dust speck in it after two years of extensive use. It’s true that dust (in a reasonable quantity) has no effect on image quality, but very disappointing for a lens of this price. I do not know how much dust it will collect in the future. Anyway, lenses are not for every year’s purchase.
I recommend this lens, if internal dust is not important for yo