oh. i guess i'm the odd one out here.
a lot of fevered comments here... although pretty certain nobody actually has one of these. I do.
my use case was pretty specific - I have a 49" LG ultrawide already (so not exactly short of screen real estate) but there are some occasions having the screen physically separate makes sense. and if I'm working late then I tend to like to have something 'on'... e.g., sports, some other low commitment event that I can flick eyes to when necessary but otherwise focus on the main display.... and having something I can occasionally beam to from the main computer would be a bonus, and also connect another computer/laptop/device from time to time.
so I went actual shopping (in an actual shop and everything) for an actual television which had to be smart. haven't used aerial or satellite in... forever. my office has neither of those things. i had researched an LG television which seemed to tick all the boxes and was absolutely convinced I was not going to buy a Samsung due to all of their TVs being reportedly riddled with ads. I saw the LG, a Samsung and a Sony alongside each other and I'm pleased I did because the Samsung was noticeably the best display. not much between it and the Sony (in fact Sony possibly better) but the LG was truly abysmal.
and having used Android on my main Sony tv; I didn't want to go anywhere near that, so swapping to Tizen seemed like a reasonable shout.
i did some more research on the Samsung devices and stumbled across these smart monitors, which seemed to tick a lot of boxes. i was originally going to get the M5 but in the end went for the M8 due to having USB-C. found one online which was nowhere near the $700 reported here (± £330 IIRC but it had to be white at that price)
and so far everything is perfectly fine. the streaming apps do exactly what I want.. usual array of iPlayer, Netflix, Prime etc. and a store with all the others if you want them. it is rapid to turn on, which probably explains it's poor 'G' energy rating. the screen is sharp and the picture quality very good.
i wasn't forced to sign up for a Samsung account... well not at first. annoyingly you do need to do that if you want to use anything beyond the default, or install a new app. or to use its voice control (called Bixby, ffs) which is truly appalling and completely unusable.
AirPlay (yes yes, macOS, let's move on) works exactly as you would expect. I can't imagine ever using the Workspace feature.
the built-in browser is a fairly miserable experience. I had one tab streaming an audio feed and I wanted to open a separate tab to load something else... which nuked the stream on the first tab.
I originally had wanted your average TV remote (since primary use is streaming apps) but that is where it quickly falls over if you do want to do anything beyond that. fortunately most apps support logging in from another device nowadays which is good, since just typing your credentials would be a tedious experience, although I doubt that's unique to this device.
but it was tedious enough to the extent that I started trying to work out how to remote control it. I can't imagine ever using the remote desktop feature - I misunderstood that when I was researching because I assumed that meant i would be able to e.g., VNC *to* the monitor; whereas that is for connecting from the monitor *to* another device. I guess that could make sense, maybe, for some things... maybe? I used the built-in browser and just getting to the page I wanted was a nightmare and it seems like the only option there is to attach a keyboard/mouse to it as opposed to being able to actually remote control it.
I've not seen a single ad yet; although I'm not sure if that is my PiHole doing its job or if they don't bundle these monitors with that stuff like they do on the TV. I've no doubt it's shipping every last detail back to whomever pays well enough but, that I'm not convinced that's any different to anyone else anymore.
anyway, tl;dr, for my use case, this thing is doing what I wanted it to do, pretty much. If it was possible to VNC it that would be great but beyond that, it does what I need.