So I made my switch from my Nikon F3, using primes to digital, and purchased an EOS 20D with the 17-85 lens.
This lens has a useful focal length range, and I don't have any complaints about its sharpness. Yes at 17mm wide open its not tack sharp, but it's good enough for my purposes. I shoot mostly portraits, and here is where I have my problems. I would have liked a little more range, say 100mm, and the f5.6 is crippling in natural light. Yes, IS helps, but your target has to hold 100% still. Background blurr... forget about it at f5.6.
But... for most purposes its a great walk around lens, and does the job well. Build quality isn't L, and it isn't AIS manual Nikon, but it is acceptable. Certainly better that the ridiculous plastic feel of the 18-55 kit lens.
So need a lens that will do 80%+ of what you want. Isn't too heavy, and has a very good focal length range.... then its a hit. But IS is not a trade off for fast f-stop, no matter what the sales guy says.
I'm keeping this lens, and just added a 85 1.8, and a 70-200 F4, and I think I've got what I need. Although I will try out the new 24-105 f4 when it comes out. I know the price is double this lens, but the range is better for me, the 1 f-stop pick up is appealing, and L is still L.