I acquired a used copy of the 24-85mm EF USM as part of a larger deal. It was a thow-in. I wasn't looking for one, but now that I've got it, I played around with it. First impression was that build quality was really not great. The barrel slops around dramatically, and if the held vertically, the zoom will slide right out to the extent of its range.
However, when I looked at the pictures I took (30D) I was pleasantly surprised. Many of the shots are quite sharp, color and contrast are nice. The focal length (equivalent to 38-136mm on a 1.6 sensor) is a pretty handy range for a walk-around lens. it's small and lightweight. USM AF works fast. Very easy to live with while travelling.
It's certainly not an 'L' lens, and it's not very fast; but, it's a pretty decent compromise (price/performance) for a travel lens.