Steve Huff isn't a zoom guy, so the fact that he admits to wanting the new FE 70-200mm f/2.8 GM speaks volumes about the quality of the new lens. In his review, Huff writes: 

"During my use with this lens [with an α7R II] I was secretly wishing that I had $2600 laying around with nothing to do as I wanted to buy this lens. I wanted it badly. Not because I need it, or would use it every day but because I have a thing for quality glass and cameras. I know one day I will wish I had this lens for a trip, vacation, specific shoot I am doing or just to have an amazing 70-200 on hand. If I were indeed a zoom guy, I would have ordered this one months ago when it was first made available. It’s a no brainer to anyone who loves this focal range and are looking for a top tier 70-200 f/2.8 lens. Sony’s GM line is stunning, all of them. The 24-70, the 85 1.4 (a drool worthy lens) and now this 70-200 f/2.8. OMG, I just realized that all three of these would offer up the best of all worlds.

"As for this 70-200 GM, it is the finest 70-200 I have ever shot with from build, feel, IQ, color, image stabilization, contrast, pop/depth, etc. There is no question to this lens' quality. Shoot it in the desert heat, shoot it in the Seattle rain. It will deliver the goods."

See the complete review at SteveHuffPhoto.com