Well since you asked..
I have one.
I really like it - AF is quick and accurate, sharpness is bang on, I'd even go so far as saying comparible to my 70-200 IS although I haven't pixel peeped enough to really say for sure.
Weight is not too bad, although I use a monopod a lot when doing my rally photography. It is just very nice to use - and I rate that a lot in my gear.