I love my copy of the lens....it does not have the PF some seem to have and is sharp at 300mm. Enjoy your new lens and you may consider adding the tammy 1.4 x tc which will make it 420mm at the long end. My results have been very good using the tc though focus will hunt a lil bit but nothing bad.
Ya I am really liking my copy of the lensas well. I have not tried it with a Teleconverter yet so it will be interesting to see how it looks when I do.