The price of this lens seems really good for what you get. I currently have the EF 75-300mm F/4-5.6 III USM lens. Would I notice considerable differnce in going to the L lenses? Enough to go ahead and buy the 70-200mm? I mainly will be taking portraits of my wife and daughter, and pics of my dogs in the back yard. Will also be using it for my vacation to Rome later in the year. Other options that I am looking at is to just wait (after my vacation) and possibly get the 70-200mm f/2.8L or wait even longer and get it with IS. Any thoughts? Are there other brands that I should look at that are as good or better and cheaper? I have a Rebel XT body, and I really don't see me upgrading it right now, I love that thing!