TLDR: it's a dud, choose something else
Quick notes:
1) I'm usually very critical of the stuff I buy
2) I haven't used a Sony TV since Trinitron back in early 2000's
3) This is my first experience with Android TV
With this out of the way, here goes.
Unboxing and assembly. I have never had an assembly instruction manual make me feel dumb before, so this was a first for me. I tried following the instructions, but I ended up doing EVERYTHING wrong. Apparently you're supposed to lift the box off the TV, not lift the TV from the box. Legs assembly works opposite to what's on the picture which will want you believe it requires 2 people and a nuclear-fuel-handling level of process complexity. It is in fact super simple - click them in place, and you're done. Just don't try to understand the damn manual.
Setting up Android. The good news is that there's an easy way to set up your Google account on the TV by using a QR code and the Google Home app. The bad news is that it didn't work - I kept getting "Your TV could not be verified" error on the app, so I ended up entering username/password the old-fashioned way - with onscreen keyboard and the d-pad on the remote
Using Android. It's been a week and I still don't know what's the advantage of having my Google account on my TV. Also, it's not quite right to call this "Android TV". It's more of a TV with Android. It appears to be casually switching between pure TV firmware and Android; but rather than creating a seamless experience is feels kind of schizophrenic. As an example - let's say you're using CEC to turn on the TV via Xbox. The TV screens start flicking between its different personalities. First it turns on and loads the standard firmware, then it loads Android, then it loads whatever streaming app was running when it switched off the last time, then it senses there's an HDMI input but can't figure out what it is (even though it was powered on by that input), then it realises it's Xbox and switches back to normal firmware and gives you the Xbox screen.
Connecting devices. Only HDMI 3 and HDMI 4 support HDR - it doesn't actually say that on the labels. Since HDMI 3 is ARC you may as well connect it to the receiver, and the Xbox/PS goes into HDMI 4 (unless you have a 120Hz 4K compatibe receiver). I had to watch a Youtube video to figure it out because it doesn't really say that anywhere easy to find.
Turning HDR on. The TV recognises that you've connected the Xbox Series X to it, but it's not smart enough to automatically turn on HDR. In fact, the Xbox is going to tell you that your TV isn't HDR capable. You need to go into settings and configure it manually. Apparently, it works seamlessly with a PS5 though.
Xbox setup and calibration. Talking Xbox calibration - someone should tell Sony that placing the main Settings menu along the right vertical means you can't see the calibration instructions that Xbox is putting on screen. I ended up just guessing what the Xbox was asking me to do. Kind of. To be fair, this finger can just easily be pointed at Microsoft though, but I suspect there are way more Xbox owners than X90J buyers.
Picture quality. The picture is amazing. Colours are vibrant, blacks are really really black. I'm not an expert, all I can say is that I really like what I'm seeing. The caveat is that I upgraded from a 42" 1080p, so I suspect I'd have had the same reaction if you put me in front of a 55" 4K Veon or something.
Gaming. When this TV launched there have been complaints about choppy motion, jitter, and lag, which have since been resolved with a firmware update. No they haven't. I don't know if the firmware story was bs, or if there's simply no au-nz version yet, but everything this guy here talks about in his well-substantiated rant - it's all still there.
Bottom line. This TV tries to do way too much, it over-complicates the core features and fails to deliver on the more advanced ones.
The only reason I don't have buyer's regret is that I got it for a very good price, and I'm still holding out for firmware improvements. Having said that, apparently last year models were promised a firmware update too, which never eventuated. So I wouldn't hold my breath.