I've been lusting over this lens for the past 3+ years. Then the 70-200mm f/2.8 IS II came out and I wasn't sure which one to get. I could afford the 2.8 IS II, but I didn't really want to spend that much money if I could be just as happy with the f/4 IS. After many hours of researching the pros and cons of each I went with the f/4 IS.
I'm not a pro, just a hobbyist that likes taking pictures of my family. I don't shoot indoor sports or anything that really requires the f/2.8. I just wanted a good outdoor zoom lens that I could take to the park. The larger size, heavier weight and bigger price tag were of course the main reasons I didn't go with the f/2.8 IS II. I'm sure the bokeh is creamier and performs a lot better indoors in lower light conditions, but I wanted to go with a lighter lens that I would bring with me more often. I have the 24-70mm f/2.8 L and I thought that was a pretty heavy lens (2.1 lbs). The 70-200mm f/4 IS is lighter than that at 1.67 lbs, while the 70-200mm f/2.8 IS II is 3.29 lbs.
The research on this forum from other members helped out a lot. I also found another post on dpreview that really influenced my decision: Owner's findings: 70-200 f2.8 II AF, etc. compared to f4 IS
. I just wanted to say thanks to all the members out there that actually take the time and effort to do reviews or give their personal opinions about a product to help out the average joe schmoe like me. I'll be looking forward to taking a duck picture and I can't wait to take my almost 10-month old son to feed the ducks some bread. 
BTW: I bought the lens on eBay last night through Beach Camera with 8% BCB (it came back instantly) and $30 MrRebate.com. Yesterday was the last day for Bing CB. 


