I’ve just bought the new 5K Apple Studio Display, and I have to say, I’m amazed by it.
It’s replacing my old 27" Apple Thunderbolt Display (2560 x 1440), so this is basically four times the pixels in the same space. The difference is incredible. It’s like getting new glasses!
macOS has removed sub-pixel aliasing, so if you’re not using a high-density DPI display, text does look a bit crappy.
But this is really crisp – staff lines are super-fine; text is very smooth, and ‘you can’t see the join’. The brightness is also stunning – in fact I had to turn it down and put a yellow tint on Dorico’s page background, cause it was so bright. You can see the full gamut of greys in macOS’s UI scheme…! 
But it’s basically the same quality as a Retina laptop screen, but much bigger.
My 2018 Intel Mac Mini (with its Intel UHD 630 graphics) was struggling to push pixels for the Studio Display (and a 1080p second display). Some of the screensavers were a bit stuttery, and it was running quite hot.
But my 16" M1 Pro MBP handles it with utter indifference, and still isn’t warm. Supposedly, it can cope with 2 x 6K displays at once! Plus I love the fact that the Thunderbolt cable that connects the display charges the laptop!
The speakers are incredible, too – I was using a pair of Bose externals, but they’re redundant now. I’ve got a 7-port USB-A hub plugged into the display, with all my peripherals attached, so I can unhook my laptop with no bother.
The microphones are very good, too; the webcam works well, and the Centre Stage gimmick is quite fun.
Dorico looks absolutely beautiful on it: all the different UI colours are clear; the notation is crisp and smooth.
One other thing: it manages to use one third of the power of my old TB Display, so with the latest energy prices, it’ll pay for itself in 10 minutes!
(UK people of a certain age may recognise the monitor stand as one for a BBC Micro - still doing service after all these years!)