A few thoughts about the A7RIV after using it this afternoon on a coast walk.
1) The ergonomics are so much better, the grip is deeper, more space between grip/lens and little fingers has a home
2) It feels better built in terms of doors, covers etc and the little things like exposure compensation lock.
3) Autofocus is really good, certainly more responsive and less laggy than the A7RIII. Eye AF was sometimes jumpy on the III but seems better now.
4) EVF is better, could tell the difference straight away. For some reason though it doesn't appear to be the boost in res that it says on paper. In certain situations ie portraits etc it looks great but for fine details on landscapes (which I do mostly) it still appears pixelated even when view taken images. Not as good as the Fuji or Nikon which is a little disappointing
5) Rear screen is the same (on paper) but seems a but brighter, maybe I'm imagining that though as only used it one afternoon. But still not proper touch, why ohh why..
6) Image quality/detail - AMAZING! I'm used to images from A7RIII and my D850 but the jump to 61MP is amazing. I was a little concerned about it being fussy with lenses but I used 5 lenses on it today and no problems, 16-35, 24-105, 70-200, 85, 90 so I'm assuming rest will be fine. Not tried the pixelshift thing yet, I'll try that in a Cathedral or something next week. Dynamic Range seems very good, not done anything techy to test but under/over exposed and recovered detail well. I'm very happy with this and worth an upgrade.
7) Files take a while to write, I'm using 300mb/s Lexar cards and they took a while to write. In continuous (high) shooting it hit buffer around 28 shoots and took a while to clear, you could watch it the counter go down slowly. It did let you start shooting again but very slowly and not much else you could do. Not really a problem, that's what the A9 is for (and please Sony release A9II soon...)
8) Menu system etc same ol, same ol... ie terrible. With so many menus it's amazing how much you still can't customise.
So far so good, Sony have made a great camera but they need to start looking at usability, it still lacks a lot of features I'd like and it lacks the intuitive feel you get with the likes of a Fuji.