Summary: For less than $600, this is the best Canon telephoto zoom lens on the market. Picture quality is almost as good as primes. Autofocus is extremely fast and quiet.

I have both this lens and its bigger brother 70-200mm F2.8 IS. I took some test shots on both lenses. From F5.6 and up, there is absolutely no difference in sharpness or color between 2 lenses.

For people cannot decide among 3 different versions F4, F2.8, F2.8 IS: Get the F2.8 IS if you have the budget, or F4 for its low price and light weight.

This is the least expensive L lens, but probably the best one to start your L glass collection.

Summary: This lens has been an absolute pleasure on my Canon Rebel XT (350D) body. I find that I use it for wildlife and sports more than anything, as the 1.6x crop on my 350D makes the short end of this lens pretty long for most other shooting that I do.

If you're looking to blend in with the crowd, you won't with this lens attached to your camera body, unless if you're with a crowd of fellow photographers. The white color and size of this lens compared to what most people are used to seeing will make you stand out. I don't mind this, as I find it amusing when people come up to me and ask which newspaper I'm shooting for, when I just take photos on my own as a hobby that I'm not paid for. Stealth isn't exactly a feature of this lens, unless if you camouflage it... :)

I don't think you can find a better lens in this focal range at the price they sell this for. This lens is a bargain for being a Canon \"L\" lens, along with it's great sharpness, color, and build quality. I highly recommend it. If you don't end up liking it, the resale value of used Canon \"L\" lenses is pretty high and consistent, so you'll get most of your money back if you decide to sell it (like after upgrading to a 70-200 f/2.8 IS :-) ).

Summary: This lens is fantastic. An L-series lens for approximately half the price of others in the series, with almost no loss in performance. Great for wildlife photography, as it focuses almost instantly and accurately.