eBay DOD: Canon EF 24-105mm f/4L IS USM Autofocus Lens - $800 w/ FS

Quote from preppyak : Yeah, except if you were using it indoors, you'd find it unsharp because your shutter speeds would be so slow (1/8th, 1/15th, etc) that your subjects would all have motion blur. It's user error of course, but, its definitely not an indoor lens unless you are using flash

I understand what you ar esaying how ever saying the lens isn't sharp then comparing it to a non L lens is not the correct termanolgy. You should reference they the apeture is not large enough to use on indoors low light photograpy, the lens is plenty sharp and probably even sharper than the 17-55 you referenced (although that lens is near L quality).
Also I will point out that unless you are just shooting candid you should be able to work around and use F4 and a higher ISO indoors with great sucess and still acheive sharp pictures depending on the final output i.e. web, 4x6, 5x7 prints etc ...