I've used it for 11 months and it has been my most used lens during this time. It's fun to shoot with, and produces good results although it has its own characteristics/pecualiarities. I find it shines photographing subjects in rim light, and when the subject is colourful. In low contrast, dull light I don't like the results too
much and prefer conventional optics for such situations.
I find the autofocus a big improvement from its prefecessor (the 300/4D AF-S) and I now can safely use it for sports with great results.
Of the VR: my lens does not exhibit the anomalous VR performance (softness, double image) at 1/125s+-2/3stop. I find the hand held sharpness is decent in most shots at 1/50s but it steadily improves towards faster speeds. Yesterday I noticed my concert shots were slightly blurry at 1/500s but as I switched to 1/1000s they became consistently excellent. Admittedly the subjects were musicians and not perfectly still. Even for stationary subjects I see better consistency of sharpness at fast shutter speeds than slow (hand held). I normally use a tripod for static subjects though, and hand hold the lens for people/action. I just checked a few shots at 1/100s with and without VR at night indoors and turning VR on improved the sharpness dramatically.
However, others have shown that there are problem combinations of camera/lens samples that produce distinctly bad results at these intermediate shutter speeds. I would take a pragmatic approach to this and buy from a dealer which allows you to pick and test until you find one that works correclty with the cameras that you have.
I love this lens because it allows me to include a long focal length in my kit with minimal weight and bag space penalty. It is not perfect but it's a fun lens to work with and I rarely leave it out of the bag. In low contrast light, low contrast subject matter such as skin tend to be rendered "milky" for lack of a better word. I don't like this aspect of the lens but I've learned to use it in circumstances where it shines. I guess that is the trick with any lens. The 200/2 II by contrast produces more 3D and contrasty faces even in soft light, while maintaining very high sharpness of fine details, but it weights 4x that of the 300/4 PF ... so it has become a much more difficult decision to use it in my day to day shooting than the 300 PF.
I think the images from the 200 are better in soft, dim light but for the right subject matter the 300 PF absolutely shines as well (more contrasty/colourful subject matter and light are needed for that, however).
I have thought about getting the f/2.8 version for many years but never got around to it. Nowadays I am quite happy with the f/4 PF as it is so practical and fun to use. However it is good to keep in mind that if you want the very best image quality especially in low light the f/2.8 is no doubt better. Somehow this no longer bothers me.
One of the advantages of the 300 PF is that you can use it pretty much anywhere and people don't pay attention to it.
For nature photos I've used it for close-ups of flowers and other detail shots, and it works well for that. I have used it for some deer photos but was unfortunately not close enough for frame filling shots with FX. I think for long distance the sharpness is good but the contrast loss due to atmospherics may limit the resulting quality.
