I have the canon 17-85mm i wrote a bit about it the other day for my website (rant site really) i copied and pasted my thoughts on it below. . .
I don't know if i'd upgrade too it, though its certainly better than the 18-55mm.... personally id get another prime or some macro tubes
Canon 17-85mm F4-5.6 IS USM 'Macro' EF-S - Review/Opinions
Often seen as the upgrade to the kit 18-55mm kit lens that ships with most XXXD Canon cameras, this lens is also bundled with some XXD range machines.
At a reasonable price point this lens will undoubtably appeal to many, and appears to sell well from many used outlets.
This lens offers an set-up in build quality over the stock 18-55mm, the more rugged build quality and increased focal range are certainly beneficial. As is the built in Image Stabilisation, real time manual focusing override, internal focus and large zoom ring.
Having owned this lens for about a year I'll try to get away from the technical/spec view and try and give an over view or users opinion of this lens which I hope will be more helpful than a list of chart scores. . .
I'm constantly considering selling this lens, yet I still own it . . . its really just too convenient!!
Its not particularly fast aperture wise, at F5.6 at the long end it quickly becomes limiting but the range of 17-85mm really does make up for this.
As a walk about lens it really excels, yes a 24-105mm,24-70mm or a 17-55mmF2.8 may beat it in most regards but if your considering this lens chances are you can't afford or don't see the need for one of those.
In all real world situations its plenty sharp enough and the IS somewhat makes up for the slow aperture, the focus seems fast and consistent.
Colour reproduction is fine, the only real issue i've had is chromatic aberrations. . . that purple/magenta fringing in high contrast scenes. It's bloody annoying and really does affect images from 17mm right through to about 24/35mm, a major turn off? Well maybe not a few clicks in lightroom and its not a problem. In fact I correct this on import so don't even notice it anymore.
Some may complain about barrel distortion at the long end and some noticeable vingnetting, again most editing programs sort this out without breaking a sweat through pre-programmed calibration settings.
And at the budget end of the market you really do have to accept these as problems you are going to face.
Another facet of this lens would be its 'Macro' designation, now this isn't really a macro lens but its close up abilities can yield some really acceptable results.
The rendition of out of focus areas or 'Bokeh', is generally pleasing for such a slow lens and at this price to complain would really be stingy, as its not a bokeh machine its general zoom. . .
If you need the push to purchase this lens a flickr search for images taken with it can yield some spectacular results.
I still own this lens despite its faults, i'll probably keep it too as its just too easy and versatile. . .
If its not for you, the Tamron 17-50mm F2.8 (VC and Non) get a good rap, and some rate the Sigma offering, both of which are of a similar price point.
