The bigger the gap between the wide and tele ends of a lens the more mediocre the lens will be. There is an L lens that is 28-300 which goes against the norm but it has a price to match.
You'd be better off with probably the 17-85 IS and the 70-200 L IS (2.8 or 4).
I will be interested in the replies to this, as I was considering buying it (or a third party similar ranged zoom) for travelling. Without any doubt you will lose on quality with an all-purpose super-zoom, but I don't know how much.
I purchased this lens a few weeks ago as a replacement for my busticated 17-85. It has not come off the camera since. I quite like it and am very pleased with the images it produces.
I got this lens in May and used it for a few days at Disney World. While it was convenient, even for just holiday shots I was not impressed with the image quality. Don't get me wrong, it is possible to get some good quality shots but the conditions need to be ideal.
I spent 2 days shooting for the pigeons challenge. The first day I used this lens, the second I used my 70-300mm Canon lens. The difference in the quality of the shots was very noticeable, even though the conditions were similar. Ironically the shot I entered was taken with this lens and it did quite well, but I think that was more because of how I processed the image than the fact that it was a great technical shot.
My take on this lens is that it's great if you want convenience. If you want image quality go for something else.
