I've had this lens now for around 2 weeks and I am happy with it. It's comparatively cheap, light in weight and produces good IQ but maybe not sufficient IQ for professionals.
Lens creep is there but there is a lock feature, activated only when the lens is not extended.
Obviously much lighter and slower than the 70-200 f2.8L IS II which I sold and replaced with this as I rarely took it out on walkabout due to the weight - I may well miss the IQ and speed occasionally but if the lens ain't used then both of those attributes are irrelevant.
Auto focus is rather good, very quick and very quiet and accurate as far as I (and Reikan FoCal) can tell.
Bought new for £285 from E-infinity - the price has subsequently already dropped a little so it's a bargain IMO.