Guys, lets not get into the argument of what is better than what, splitting hairs.
Step back, GET the lens, handle the 17-55 and then come back comment on the lens la
Pls can someone with the 17-55 lens comment more on their experience and post more samples? As far as I am concerned, it is slightly sharper than the 17-40L i tested on a newspaper cutting, and that speaks alot on what it cost $1.9K. To me the 17-55 2.8 is definitely more useful on my 30D than a 17-40 f4 or 16-35 f2.8 NOW. It serves me better on my 30D. No point to me to get the 17-40 so that just in case I upgrade FF next time. I can start taking technically better/ more useable pictures now with the 17-55 with IS f2.8 now, more than the 17-40L. If upgrading to FF, then sell everything la before upgrading to FF lens too.
The downside of the 17-55 is its build, if only it metal-encased, like the 30D. And it extends quite a fair bit, unlike 17-40 or 16-35, small issue though. and of cos the high cost. but hey, imagine a 17-55 f2.8 IS L for full frame, it would have costed $3000+ easily (considering that 16-35 f2.8 L is oredi $2.3K). So it is still relatively "cheap".
Other than tat, this lens performs. If want quality, no need to shy away from it.
Strange, nikon and canon got their own series of lens, so no point cross comparing oranges and apples
just my 2 cents.