My quick take on this TV/Monitor:

The good

• Very good for the price (I paid $299 at Costco, new)
• Super blacks and excellent separation at the low end, like, if you have a piano next to a music stand you can see that they are both black but they are a different type of black.
• Good color, I calibrated it to 99% RGB in about ten minutes with my Spyder 4.
• Not much bleed at edges
• Very, very sharp text if UHD is enabled
• If you plug in a USB, it will play videos and also show JPEGs. The JPEG viewer is very good quality.
• Thin bezel
• Silent, relatively low power, not hot (remember the plasma space heaters?)
• My monitor/TV came with no dead pixels and a very nice pixel pitch. Close up, you aren't really aware of pixels.
• You can render out your vid, put it on a stick and play it through the TV. The speakers are nothing special but you can use them, for sure.
• BIG

The bad

• Awkward at framerates--if you work in 24p you won't like the cadence, but I find it OK for editing nonetheless.
• Some input lag, even though slight
• 2160p isn't ideal for editing, better to have a slightly taller ratio
• Backlight dimming is unpredictable, AFAIK.
• Not so easy to calibrate as a TV, relatively easy, however, to calibrate as a monitor.
• Uses PWM, so if you dim it, it can be blurry. I didn't notice this but some ppl are more sensitive to PWM.
• Needs HDMI 2.0 or higher for full color, or an adapter of some kind. Your card may not support higher refresh rates (mine does, but I may get a better card anyway.)

Overall, kind of a no brainer. It looks great, and it is dirt cheap. You can nitpick about the framerates and some of the tweaks but it is, after all, the bottom of the 4K lineup.

Question, not answered by the manual:

If I play an HDR video either via the HDMI port or through the usb port using the TV player, will it know it is HDR? Is there a setting for HDR video, or does it require metadata, or what?

Similarly, if YouTube plays an HDR video, will it detect that the TV is capable of HDR? Or does, again, something need to be set on the TV?

@Vitaliy PWM makes it look weird to me! It looks to me like the PWM only cuts in below 60 percent of the brightness, so I just keep it at 70-80 percent.
Re the backlighting--you can't control it so sometimes it affects the tonality across the image when grading. It's a minor problem, but definitely a problem. Maybe there is a hidden setting to disable it... Many large monitors have problems with grey uniformity across the screen, the Samsung is decent, but I wouldn't call it great. It is definitely not the power saving feature as I turned them all off.
Re 24p etc I don't think the monitor supports 24p, unlike my seriously cheap Vizio, but I will see if there is an app for it. An app won't help with playback from the USB. There is also a film mode that is greyed out. I have tried the judder removal on low and it seems to help, but it isn't 24p. On my Vizio, it just switches to 24p automatically (however the newer Vizio model that I briefly tried did not.....). Also, on the Vizio, if you hit the info button it shows you the frame rate. The Samsung shows just the resolution.

Input lag-- No biggy. Not a deal breaker by any means, and I don't use it for gaming. Of course, it is a lot of real estate to cover.

@Mark041 if you have an HDR sample (small) I can put it on a stick and play it. I haven't tried the YouTube app yet. In the menu you can turn on Auto HDR--the short description says it will then turn itself on or off depending on the source. From what I hear, at this price you won't be thrilled by the HDR mode, but it is present.

Hey, it was $299......and black is pretty black.

Note - Colormunki deal today

https://www.personal-view.com/talks/discussion/18307/x-rite-colormunki-display-for-99

24p update: the TV does show the frame rate, but only for a few seconds when you turn it on. After messing with the graphics card, I did amazingly get the TV to show 24p. Shocker. However, 24p footage looked terrible. But it may be possible to get it to work. For now I'm just living with a bit of judder. If the monitor did 120p I think you could have a good 24p.
Backlight: there are some small uniformity issues. You see it only if you have a big area of black or grey.
Built in media player: I'm testing that now, as I mentioned before the JPEG display is really fantastic. It also plays my high bitrate mp4s (but still the 24p problem).

tempt to update my old desktop from gt640 to gtx 1050 Ti; a waste of money? which graphic card is best bang for buck to edit 4k with this monitor?

I’m happy with 1060 mini ,does good job inside davinic with raw and prores 4K ,it hiccups when I add ofx plugin (almost unusable frame playback ) ,not sure if that’s a davinci issue

Additional observations (it's still a very good deal).
1. Looking at some grey swatches you can see minor uniformity issues.
2. "red" is ever so slightly orange, even after careful calibration. To be fair, most monitors are kind of orangey, but the good ones have a red that is red. Possibly this is to improve skin tones....However, even my cheapo Benq monitor has a true red.

The other thing is it takes a really long time to get the mouse across town!

@DrDave

Well, you can measure your other monitors.

But in reality it is lot of things that can affect your colors perceptions, even TV frame color or changed position or fact that you have less wall visible now.

That's true, but I can still tell an orange from a tomato :)

Your colorimeter must be also able to tell you this.

The colorimeter tells the computer the formula for the best red possible for a given monitor.

Actually colorimeter has same sensitivity curves as your eye :-)

and if you use a colorimeter on two monitors, the colors will look slightly different.

If they are different it'll show you how.

vision is stereoscopic, so at a minimum you would need two colorimeters

No, you don't.

If you look at a monitor at a slight angle, the color shifts.

True. OLED and IPS are best in this regard, PVA is worse and TN is much worse.

and check PM.

UK offers (338 GBP and up)

• https://www.appliancesdirect.co.uk/p/ue40mu6120kxxu/samsung-ue40mu6120kxxu-40-inch-led-tv
• https://www.amazon.co.uk/Samsung-40-Inch-SMART-Ultra-HD/dp/B075GFRZSP

I just used my Spider colorimeter, set the TV to cool and turned the backlight down one click. Lowered the sharpening. Ran the colorimeter software. I think some ppl prefer other colorimeters but I'm not buying another one as I have several already.
White point outside of monitor land--that is, using it as a TV--looks like a PITA but I'm just using it as a monitor.