The Canon 17-55mm has an average review score of 81%

Score (%):
Canon EF-S 17-55mm f/2.8 IS USM (Tested)
Multiple user reviews on slrgear.com
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90

Canon EF-S 17-55 f2.8 IS USM
Canon makes two distinct lens ranges. The EF lenses will fit any of the EOS bodies, but the EF-S lenses will only fit Canons with the smaller APS-C sized sensor. That includes the EOS 1000D, 400D, 450D, 40D and new 50D. You can't use EF-S lenses on the pro-level 1D Mk III or 1Ds Mk III because they have bigger sensors and a slightly different lens mount. The EF-S 17-55mm f2.8 IS USM lens being reviewed here, then, is designed for these smaller-sensor EOS models. It's the biggest and most expens...
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80

Canon EF-S 17-55mm f/2.8 USM IS - Review / Test Report
The full in-depth review from photozone.de
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73