An "L" lens by any other name!

This truly is a Canon "L" quality lens minus the packaging. The optical quality is certainly up to par with Canon's "L" lenses, but the case build and weatherproofing are not. That's not to say that there is anything wrong with the build, it's typical Canon, which is the highest quality. This lens is:
1) Quick: It focuses quickly and accurately in all types of lighting.
2) Sharp: From fully stopped to fully open. I've read some reports of it being slightly soft at the edges when fully opened, but have not seen it for myself.
3) Lovely Bokeh: Absolutely beautiful, soft bokeh.
4) Smooth: Focus ring and zoom both easy to reach and use and also very smooth.
5) Fast: F 2.8 throughout the entire range of zoom.
6) Spendy, but well worth the money. If you have a good dslr, do yourself a favor and buy good glass for it or you'll be disappointed in the performance. Lens and cameras are like sound systems and speakers. It doesn't matter how good your amplifier is if you buy cheap speakers and it won't matter how good your camera body is if you outfit it with cheap glass.
One of the most useful "walk around" lenses in my opinion, with an effective range of 27mm-88mm on a 1.6 crop apsc sensor. The wide is perfect for panoramic views and the zoom is just enough for portraits. Canon's 28mm-270mm F3.5-5.6 L lens is my second lens and is the perfect accompaniment for this lens.

Canon EF-S 17-55mm f/2.8 IS USM - An Excellent Lens

I am now the third owner of my copy, and it doesn't seem to be any worse for wear for it. But then again most camera buffs take pretty good care of their equipment. My copy, perhaps just lucky me, also does not seem to exhibit the dreaded dust sucking problem that it has been reputed to have. I see no dust specks under the front element.

I upgraded to this from the 17-85mm IS f4-5.6, which is a nice lens in its own right. I am glad I did for a number of reasons:
- its constant f2.8 is great for low light and bokeh
- my 40D body shifts its center cross-type autofocus point to a higher accuracy mode with f2.8 (or faster) lenses
- it's sharp wide open, and is razor sharp at f4
- images taken with it have more "pop" (i.e. contrast and colour) compared to the 17-85mm, which is typical of L glass
- its barrel distortion at 17mm is significantly better than the 17-85mm (of course you can use DPP in post processing to further reduce)
- it can directly share the 77mm C-PL, ND4, and ND8 filters I already have
- it feels a bit sturdier than 17-85mm did
- it maintains it's value very well, and the demand is high for it in the secondary market

So it's all good, but there are some (minor) niggles:
- it maintains it's value very well, which means I paid a lot for it which I wouldn't mind so much if ...
- ... and it's the same old complaint: for that kind of money you don't get either the L build or a hood (although admittedly I was lucky the additional EW-83J hood was included in my purchase from the previous owner)
- it is big in comparison to the 17-85mm, but it is well balanced on my 40D
- I mourn the loss of the 30mm of extra reach the 17-85mm had (but I have a 85mm f1.8 and a 70-200mm f2.8 in my kit to take care of that)

In summary the lens is great as a walkaround or for indoors, and you won't be disappointed if you get it. It's considered by many, including myself, to be the best single Canon EF-S lens to date for IQ. I had briefly considered the 24-105mm f4L instead, but felt that not having the wide end was a show stopper for my walkaround needs even though I also own a 10-22mm. The 24-105mm is a perfect range on a FF body though.

Some would advise against buying this lens, or any other EF-S for that matter, because if you ever upgrade to FF you will need to ditch it. That is true, but if that time comes for you, you will have a lineup of buyers ready to take it off your hands without you losing very much from what you paid for it. Canon's 1.6x crop lineup is going to be around for a very long time.

Great optical quality from this lens!

I purchased this lens because I had the Canon EF 24-105mm f4 IS USM, and it just wasn't quite fast enough in some low-light situations that I'd been in recently during weddings. I needed the fast aperture as well as IS. I had read a lot of good things about the 17-55, so decided to pursue it.

Let me first say that I loved the 24-105mm. If it were not for the difference between f4 and f2.8, I would have definitely stuck with it. It took awesome photos, the range on it was awesome, and it was very solid in terms of build and feel. If it will meet your needs, I would highly recommend it.

Back to the 17-55:

Pros
-Great image quality
-Very usable at f/2.8 and produces great bokeh for a zoom
-Relatively light
-Focus and zoom rings are smooth
-Overall, a great performer and I can recommend it

Cons
-The build; I guess I was spoiled by L lenses (also had a 70-200mm), but the 17-55mm is very plastic-y and definitely not as solid as the L lenses I've owned. It is still superior to kit lenses, but definitely not "L" material (although I supposed if it was, and it had the nice red ring around the barrel, it would be much more expensive).
-Dust easily gets into the barrel - the zoom acts as a vacuum, and there's been quite a bit of dust that's accumulated. I haven't seen this affect any images yet.

All-in-all I would highly recommend this lens, although do not expect it to feel or handle like an L lens.

Outstanding all around lens

I started with a Sigma 17-70 F2.8-4 lens and thought it took good shots. However, after using on vacation for 10 days, I found that I had many shots that simply were not sharp, so when I returned home, the Sigma was also returned. However, I was sold on the utility of a walkaround lens in that range.

After doing quite a bit of research, it became clear that the Canon 17-55 f/2.8 IS lens was loved by everyone that reviewed it and used it. After I read a review that showed it consistently delivers sharpness equal to or better than most primes, I made the leap.

I have to tell you, this lens exceeded my expectations. The only reason I cannot get a sharp image is due to my own failing, not this lens. I can use it wide open and not have to worry about soft edges or other issues often noted when you use lesser lenses at their max aperture. Focus is fast and dead on and while the IS isn't quite as good as my 70-200, it is still terrific. Don't let anyone tell you you don't need IS with wider lenses, you do - at least with Canon's IS.

This is indeed my walkaround lens - great for landscapes and almost every other task not requiring a longer lens. The only reason to go to a prime is for a faster lens - for that, I have my eye on the Sigma 30mm f1.4.

Don't do what I tried to do and settle for less, especially if you have made the investment in a good camera (I have the 7D). Spend the money on a few good Canon lenses - especially zooms, and use Sigma/Tamron for primes and macros where they seem to do quite well.

Amazing complement for a crop sensor camera, LOVE IT IN MY CANON 7D

Excellent for crop-sensor cameras, cristal clear pictures means less time editing. I believe in getting it in camera right instead of making something up in photo shop. This lens is fast, good quality, silent, etc. If you thinking on moving up to a full sensor camera don't buy it...it wont work. For my Canon 7D this is the perfect compliment!