Update-
I still do not get any HDR on Netflix with the App on my Samsung K8500. I suspect patience is the name of the game. Amazon UHD on most content now does have HDR UHD and it is working very well.
I also bought the new Joe Kane UHD calibration files with full resolution test charts and BT2020 color cal mapping points. It comes in a USB stick but there is a technical limitation currently to the files. Joe designed these primarily to run in a professional mastering suite. While the files are great for setting up your display for brightness and contrast, sharpness, the color mapping coordinates for BT2020 will not work on our monitors so the best is to use the 50% saturation charts which will map colors to close to P3. Additionally, there is a problem that no HDR file can transfer and display from USB because the Player's USB port strips off the MaxCLL and MaxFALL metadata necessary for the display to recognize proper HDR. Joe intends to come out with a consumer version that will be sold on UHD disk form so that HDR can be recognized in standard UHD players. Obviously this is quite expensive since there is no current burner or media to do this.
There are more issues with the test chart files but these can be worked around. The BT2020 container test files are rendered in EXR file format which is an extended contrast range (HDR) special file format for loading into the
Black Magic Davinci Resolve he used. Fortunately there is a good converter that works I have tested (Photoshop sees the EXR file but is buggy and fails to properly convert it ) The converter that works is reaConverter. It seems to be a very nice tool for anyone working in computer graphics. Very simple and supports batch file conversion. While this converter can translate to jpg and BMP for the Samsung K8500 to recognize and display, we still do not have HDR metadata so the charts are only good for color coordinates within the P3 space, and BT2020 container with HDR OFF on your display.
What all this means is, the content producers have the freedom to generate colors well beyond any consumer display capability and be "legal" so that one calibration condition on hue for one disk may be different for another. The safe approach will be to produce a program disk that is about 80% of P3 color so it properly maps to all consumer UHD HDR capable monitors the same. Unfortunately, this limitation creates a displayed image that is not much better than BT709 8 bit. Content producers who render to colors beyond P3 might look great on a $60,000 Laser projector but some reds will look very bright orange and some greens very bright yellow, deep sky blue will come out as turquoise on lesser capable TV's. I suspect all this spells to a future of total confusion among the consumer buyer. For any of you old timers, this reminds me of NTSC as in Never The Same Color days.
UHD-
4K (3840 x 2160p) resolution is great and is the biggest advantage of UHD.
BT2020 has some serious compatibility problems causing the same disk to look wildly different on different calibrated monitors.
HDR is great but requires BT2020 to work.