Sharp! Esp. f5.6 - f11
Natural colour rendtion
Fast max aperture and AF
Build quality (metal mount, solid casing)
Size (actually very small - even when compared to EF-S lenses)
58mm thread
MF override
Internal focusing

The only MINOR MINOR weakness is that the zoom actually zooms the front element out, but for this price that is really not an issue. It's not really a macro lens, so it doesn't matter.

Superb lens. Highly recommended!

The 3.5-4.5 max aperture is fantastic for such a reasonably priced Canon USM lens. The AF is very quick and silent. I cannot understand why a reviewer thought it was slow.

The images are very sharp, especially from f5.6, however, I would not call wide open images "soft".

The colour is very natural and accurate. I know there is a trend for over-saturation now, but I prefer to add saturation as the situation requires in PS.

This is great lens. I have compared it with the 28-135 IS USM, which I really didn't like and the 24-85 USM which should have been as good, but was not (a lot of distortion and zoom creep on the lens). For me, this was the best investment I made on my Canon kit.