I have the 17-85mm, and I'm generally very happy with it. There's obvious barrel distortion at the wide end, but it's not offensive, and it doesn't worry me enough to spend the money on the 17-55mm, or the 24-70mm (the latter is on my list of glass to get, but it's not a high priority.)
The only drawback of note with the 17-85mm is that it is a relatively slow lens (f/4.5-5.6, depending on where you are in the zoom range.) I have no qualms about recommending it to people wanting to step up from the kit lens (the 18-55), especially if they're likely to balk at the cost of the 17-55mm.