Technically the Canon EF-S 55-250mm f/4-5.6 IS is a tiny lens with a great performance potential. The resolution is very good across the range. Chromatic aberrations are basically a non-issue. The level of distortions remain moderate. The most obvious flaw is, unsurprisingly, vignetting at large apertures. The build quality is fine for a lens in this class and it is one step up from the EF-S 18-55mm f/3.5-5.6 IS that we've seen here recently. Regarding the target market you may surely forgive the plastic mount. The AF (micro-) motor is pretty fast and silent. So's everything cool here ? Well, the AF accuracy didn't really convince in the field - specifically at the wide-end of the zoom range - but to be fair this is much better on an EOS 40D (e.g.) with its improved AF capabilities. I had some trouble with the image stabilizer in the field but according to early reader feedback this impression seems to be an exception to the rule. If so the EF-S 55-250mm f/4-5.6 IS has certainly the potential to be another hot seller.