First impressions - the new Canon 16-35mm F4 L lens

I’ve been using a Canon 5D Mark III since their release in 2013 (I think it was?!), along with a 17-40mm F4 L Canon lens. I’ve never been happy with that lens - it felt like a reduction in quality from where I had previously come (I was using a Canon 450D and a Sigma 10-20mm f4-5.6). I found the 17-40mm was never as sharp as I expected from an L lens, it suffered badly with distortion and chromatic aberration….