This may help regarding 18-55IS vs 18-55 issues. (quote from dpreview)
"The EF-S 18-55mm F3.5-5.6 looks destined to carry the flag as the kit lens sold with virtually every Canon dSLR over the next few years (and that counts as an awful lot of lenses), so it really needs to perform well in the face of some impressive competition. Fortunately for them, Canon have indeed upped the ante with this new lens; it's much better than its predecessor, especially in terms of sharpness in the corners and at wider apertures, and with reduced chromatic aberrations to boot. Indeed overall it's an extremely well-behaved little lens, with very few nasty surprises for the user, and a remarkably good image stabilisation unit; indeed Canon's main concern may ultimately become whether users have as much incentive to upgrade to more expensive optics as they did before.
Of course this is still fundamentally a relatively cheap kit lens, so all is not a bed of roses, and the test numbers don't quite tell the whole story. Local constrast is still lower than more expensive lenses, and flare can be a real problem, both likely predicated by reflections of stray light from the inside of the lens barrel, which is much less shielded than on more expensive lenses. The manual focus ring and lens hood are both nearly worse than useless, and while Canon aren't alone in cutting corners here, both Pentax and Olympus have shown that these simple features can be implemented well on a kit lens without bankrupting the company. So whilst this lens is indeed very good, if not exceptional for the price, and certainly very much better than its unstabilized predecessor, surprisingly enough it still can't quite match the more expensive lenses in the range.
In summary, this lens is a very welcome addition to Canon's range, and gives new dSLR owners a level of optical quality in the basic kit lens which was previously lacking; the addition of IS also goes a long way to increasing its flexibility. It makes an ideal lightweight general purpose-starter lens, and as such can only be recommended."
"The EF-S 18-55mm F3.5-5.6 looks destined to carry the flag as the kit lens sold with virtually every Canon dSLR over the next few years (and that counts as an awful lot of lenses), so it really needs to perform well in the face of some impressive competition. Fortunately for them, Canon have indeed upped the ante with this new lens; it's much better than its predecessor, especially in terms of sharpness in the corners and at wider apertures, and with reduced chromatic aberrations to boot. Indeed overall it's an extremely well-behaved little lens, with very few nasty surprises for the user, and a remarkably good image stabilisation unit; indeed Canon's main concern may ultimately become whether users have as much incentive to upgrade to more expensive optics as they did before.
Of course this is still fundamentally a relatively cheap kit lens, so all is not a bed of roses, and the test numbers don't quite tell the whole story. Local constrast is still lower than more expensive lenses, and flare can be a real problem, both likely predicated by reflections of stray light from the inside of the lens barrel, which is much less shielded than on more expensive lenses. The manual focus ring and lens hood are both nearly worse than useless, and while Canon aren't alone in cutting corners here, both Pentax and Olympus have shown that these simple features can be implemented well on a kit lens without bankrupting the company. So whilst this lens is indeed very good, if not exceptional for the price, and certainly very much better than its unstabilized predecessor, surprisingly enough it still can't quite match the more expensive lenses in the range.
In summary, this lens is a very welcome addition to Canon's range, and gives new dSLR owners a level of optical quality in the basic kit lens which was previously lacking; the addition of IS also goes a long way to increasing its flexibility. It makes an ideal lightweight general purpose-starter lens, and as such can only be recommended."
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