Just took it for a test ride for a couple of hundred shots with some proper photographic charts. Fast, precise AF. Sharp all the way. Best at the longer end FL, as others have noted, but overall delivers very well on the optics. Handling is not as good as the 100-400 IS L II even if its lighter. Almost macro capable. No regrets here after using the lens today as I continue to add RF-lenses to my collection. Hope to be able to test it "in the wild" the next couple of weeks.