In brief, it's fast AF, sharp @2.8 across the frame, creamy smooth and vibrant colour rendition. Nice firm but smooth zoom, and really nice and precise focus ring. I'm impressed.
Only minor negative so far is some faint onion bokeh from bright metallic oof highlights visible if pixel peeping, not a concern otherwise.
I tried the new tamron, returned it after 2 days. This best's it in every way (apart from IS) it has a similar construction to the tamron, with the rear element cluster moving in / out with zooming. But it's to a higher standard of build and optics.
Its worth the wait, (coming from someone who held off purchasing for 2 years) then gave in and bought the tamron, returned it and waited some more...