Pros: Wide zoom range, fast quiet focus, image stabilizer, 67mm, nice walk around and nice focus range even for video

Cons: Not a f2.8, not 800 dollars
Not 77mm
No optional extras (lens hood, UV filter) So get them.
Heavy compared to kit lens and a lot larger, good construction usually is.

Other Thoughts: I have even used this lens on my 7D and have shot unbelievable photos with it. It is absolutely a fantastic lens for the price. Half the price of L-glass of equivalent quality. Besides what others have said, this is a great, sturdy lens. Works fantastic even in less light. Nice all in one.

Pros: Great everyday lens, much better than the stock one, the lens I put on when other people use my camera.

Cons: not the best photos, ok for portraits

Pros: Slightly better than the kit lens
Nice zoom range
Good autofocus

Cons: High chromatic aberration
Poor edge sharpness

Other Thoughts: I wanted to have just one lens useful almost everywhere. After taking a few photos I returned the lens and bought a 15-85 which imho is a way better lens. In the center they're about the same (tho I think the 15-85 is sharper) but away from the center they're not even close. The 15-85 is much sharper, almost no chroma aberration. If you're serious and have a T2i like me with lots of pixels this lens probably won't cut it.

Pros: A much better lens than the standard one. Super fast autozoom. First I thought it was broken because I didn't hear any zoom sound... Then I realize it was so fast and quiet you barely notice it. My regular lens is more like; press button halfway.... bzzzz... doing autozoom... bzzz... ok. zoomed in.

Faster.
Quieter.
Better quality.
Sharper.

Cons: Freakin expensive.

Other Thoughts: Good lens for most shots. This is the everyday lens I bought for my Rebel T2i. It works great for indoor shots and outdoor. Not good for telezoom shots obviously...
Buy your camera with body only and buy this lens instead of the cheap standard lens.

Pros: Perfect zoom range for an everyday lens, for me anyway. Very wide and 85mm zoom is more powerful than I expected. IS is great and makes this lens so much more versatile. Incredibly fast focus. IS is pretty fast acting also.

Cons: Not as big of an improvement in focus and crispness as I expected. But I'm viewing on a computer screen only and suspect I need to print these to really see the sharpness. LENS CREEP AFTER A FEW WEEKS AND NO ZOOM LOCK LIKE MY CHEAPER SIGMA LENS. If you grab the camera and try to snap off a quick shot, occasionally you'll catch IS right as it snaps into place causing a lot of blur. You won't notice this except when you're in a big hurry.

Other Thoughts: I think they quit making this lens. Get one while you still can.

Pros: wide zoom range 17-85mm
Image Stabilizer
Quality optics/construction
Fast focus

Cons: Chromatic abbreviation in some cases at lower than 35mm
Not a f2.8
No optional extras (lens hood, UV filter)
Heavy compared to kit lens and a lot larger

Other Thoughts: If you're not sure if buying a camera for 500 bucks and then paying the same for the lens is worth it, think no more.

This lens is an absolute bargain, loaded with great optics, optical image stabilizer and ultrasonic motor it is worth every penny. A lot better image sharpness / quality compared to kit lens, better zoom, fast focus, stabilizer for low light conditions/ macro jut make this lens the best kit replacement. Like others said, it is a dust magnet so pick up a UV filter just to keep the dust off. This one is half as much as the 17-55mm IS USM f2.8 and though it does perform better in low light settings, it's not worth the price as it offers the same picture quality as the 17-85mm IS USM.

Bottom line: If you're not sure if it's worth it, save up for it, pick it up and just see the difference. You won't want to return to the stock lens. Ever again.

Pros: Best walkaround lens for the price for a cropped body (Canon 20D,30D,40D,XT,XTi,XS,XSi). Even though I have several L-lenses, I still go back to this lens for those casual family photos and outings.

Cons: It is a dust magnet. Put a lens filter on this lens and you'll prevent most of the dust from entering into the lens.

Other Thoughts: If you could afford the more expensive EF-S 17-55/2.8 IS USM lens (also available here at NewEgg), that is a noticeably faster lens (fixed f/2.8 opening).

Pros: I have a digital rebel xti and have been using the stock (18-55mm) lens that came with the camera. With that lens every now and then I would get a crystal clear shot. With this lens almost every shot is crystal clear. When I took the lens in my hand it almost quadrupled the weight of that awful stock lens, to me that means better quality.

Cons: I love this lens. Didn't zoom as far as I thought it would, but thats my fault for being dumb. Looks like I'll need a telescoping zoom lens to do that.

Other Thoughts: I am not a photographer, I bought this lens for my girlfriend. This lens arrived TWO DAYS after I purchased it. GO NEWEGG!

Pros: This is the first lens I've bought besides the starter kit lens, and it is an incredible difference. The range is longer, the USM motor is fast and quiet, and I don't know how I took pictures before IS. The IS on this lens is 3rd generation and it really works, especially indoors and low-light conditions, it makes a huge difference. Really, if you're looking for an all encompassing walk around lens that won't break the bank, this is the lens for you.

Cons: I bought it for less from Craigslist, but this is still a good price. Its an EF-S mount, so it won't work on some cameras. Check yours. I wish the range was a little longer, like 100mm, then I'd never need another lens.

Other Thoughts: Because it is an EF-S mount there is a crop factor of 1.6. This means its range is really more like 27-136 on a EF mount. I compared this till the cows came home against the 28-135 and I'd recommend getting this one. Also, pick up a UV filter and a lens hood while your at it.