In some ways the cheaper 18-70 mm and 18-55 mm lenses do the same or more and cost a lot less. This professional 17-55 just feels more solid and inspires more confidence and is a stop faster. The images aren't any different.

It works great, which it had better do for $1,250. It feels right: it's solid metal with engraved markings. Don't pay extra for it if you're hoping distortion would be gone: the $150 plastic 18-55 mm has similar distortion at the wide end and much less distortion at the long end!

Buy one if you need to look tough and have a lens you can use for self defense. Personally I prefer my lighter 18-55mm kit lens, which gives about the same results optically for digital, even the D2X. Digital isn't very tough on lenses compared to what we did with 35mm film. I'm not particular to needing f/2.8 for low light; I use slower lenses and crank up the ISO.