Conclusion: Got this lens (separately) since the reviews were pushing it over any other lens for a crop body. The price was cheaper too, so why not?! I've had the privilege of using this lens for almost 2 years now and here's what I've noticed. It takes reasonable pictures. Not stellar, but far from bad. It does produce at times somewhat soft results which was a little bit disappointing.
Pros: good quality build, easy to use, reasonable picture quality
Cons: Semi-sharp images, bulky, heavy, hunts in lower light, designed for outdoor mostly
Conclusion: This is a great lens for outdoor photography. Pair it up with one of the the 70mm-200mm L models and a 50mm 1.4 and you can get most anything done you want. It is not the greatest for indoor stuff like school functions etc but then it likely wasn't built to be.
Conclusion: I am surprised at the reviews that say this is not a sharp lens or that the kit lens is sharper. Mine is very sharp. If I had to express one complaint that would be aperture size. It would be perfect if it was F2.8. The vignetting issue reported in some tests is not something I have noticed in real life. The other issue, barrelling is apparent in the view finder but less so in images. As it is consistent, it is not so noticeable.
Pros: Fast auto-focus, Superior build quality, Super-sharp images
Conclusion: I bought this lens (I have two) about 5 years ago and I have shot a lot of weddings with it along with other photo sessions. It has been my all around lens for travel. It has been a great all around lens. I had other 3rd party lenses and they don't work half as well. This lens is quick to focus, quiet, and sharp. Like everyone else usually comments, this lens would score a perfect 5 if it had a lens lock.
Pros: fast focus, quiet, sharp, great all around lens, has a good feel and weight
Conclusion: I purchased the lens together with my 60D and I am very happy with the results I got. Nice and sharp images, very fast AF (one of the best in the market, if only contrast detect AF could be comparable....), effective stabilization. It is a bit heavy, considering it is not 2.8, but a good balance on the 60D. It is more expensive than the competition and, for the price, Canon could have included a hood.
Pros: fast af, effective is, good build quality
Cons: a bit heavy, not very small, lens hood not included
Summary: I like the canon 15-85mmm lens for it's focal range. It makes a great walk around lens. The one disappointment I have, is that I don't think it is as sharp as I thought it would be. Maybe, I got a bad copy. I bought it off ebay from a person who said they only used it one day so I thought it would be perfect. It had a big focusing problem when I got it. I sent it to canon and I was lucky, they recalibrated it.