Have been playing with my new Apple TV 4K 64GB for a few hours. I really want to like it. Here are some first impressions.
My TV: 2015 Sony XBR75X850C (supports HDR10).
My receiver: Denon S910W. I have a 5.1.2 ATMOS speaker setup.
I also have the latest Shield TV and a Sony X800 4K blu-ray player (both attached via the Denon). I recently got rid of my XBOX One S as it was a terrible HDMI CEC citizen.
(+) After making lots of picture adjustments, I love the picture quality from the Apple TV 4K for apps like Netflix, HBO Now, Starz, Epix, etc.
(+) Most items almost instantly go their full resolution when streaming on the Apple TV. On the Shield, sometimes Hulu, Amazon and Netflix take up to 30-90 seconds to go to full resolution. Everything is gigabit ethernet connected on my home network with a 300Mbits internet access. Sadly on the Apple TV there's no way of knowing what the actual stream stats are, but just by observation, content from Hulu, HBO Now, Netflix look pretty good - like they do on my TV's native apps which are the benchmark for me. The shield does NOT excel with its forced upscaling of 1080p - the Apple TV does a better job.
(+) 4K HDR content on Netflix and iTunes Movies look pretty good. About the same as my Netflix native app on TV (my benchmark), and 4K HDR movies on iTunes are "close" to disc 4K blu ray player - tad softer than 4K blu-ray disks, and a tad less bright on the highlights. Very little difference.
(+) Sound quality on the Apple TV is pretty awesome even though there's no bitstream. I do love ATMOS on my Shield though.
(+) Some of the non-HDR things look pretty nice due to the forced HDR mode, including Game of Thrones on the HBO app looks like how I'd imagine the HDR version of that show would look like when it officially comes out. For comparison, I think the XBOX One S also locks picture mode to the highest content in the app (4K/HDR etc.) at the app level for ALL content in that app. The Shield also forces 4K upscaling (inferior to Sony TV's upscaling) instead of sending native resolution and frequency, but does not force HDR mode. I hope the HDR conversion of non-HDR content improves over time and is made optional, so those who don't want it can turn it off, and I can leave it on.
(+) A few of my movies on iTunes got promoted to 4K HDR. Awesome. This, and the cheaper 4K HDR content might be the ONLY reason I will hold on to the Apple TV, although there is some bad news right below here.
(-) When Apple TV is attached to Denon, it permanently leaves the Denon output (hence the picture setting for HDMI input on TV where Denon is attached) to HDR. So if I then try to play the Shield, which is also coming via the Denon, it is hard coded to HDR. When attached via the Denon, HDMI CEC stuff works well between the Apple TV, TV, and Denon. For example, I can control the Apple TV using the Sony TV remote, and I can change volume of Denon from Apple TV remote (via HDMI). But since it "takes over" the Denon output to be always HDR even for the other devices attached to the Denon (or rather leaves the picture setting on TV's HDMI input for the Denon's permanently to HDR), I cannot have this config. Even turnign the TV and receiver off and on does not let go of the HDR mode on that input. Bizarre thing number 1.
(-) Because of the above issue, I connected the Apple TV directly to another HDMI input on the TV, so that that input would have its own HDR picture setting and my other devices on the Denon don't get locked to HDR. This is especially acceptable since the Apple TV does not output bitstream/ATMOS etc for my Denon to take advantage of anyway. However, in this config, I lose HDMI CEC control between the TV and the Apple TV. The wonderful HDMI CEC interplay described above is gone. No mroe control of Apple TV using Sony TV remote (not a big deal), and no more Denon volume control from Apple TV remote (I have to switch it to control TV volume via IR to use the Apple TV remote for volume control). Bizarre thing number 2.
(-) Plex app on Apple TV is a disappointment. Does not play any of my HDR files in HDR (TV is in HDR more of course, but colors are washed out). Secondly, all 4K files take forever to start streaming on Plex. They play beautifully and instantly via the Shield. My Plex server is a Mac on the local network, not on the Shield, so Shield has no configuration advantage here. Hopefully the Plex app will be updated soon for proper 4K/HDR support on the Apple TV. The app currently fails when playing files that have ATMOS sound encoding. Just aborts playing those right away.
(-) No Amazon, no 4K in Vudu or YouTube. I expect these to be resolved soon (at least we've been told by Apple regarding Amazon).
(-) The Apple TV remote becomes unresponsive for a few seconds occasionally. Same with my Shield TV.
Please forgive any non-clarity in my points above. I'll gladly clarify.