Solid review from Apple Insider. My concerns are about functionality and price.

On functionality:

If you want a set-it-and-forget-it box for your 4K television, HDR or not, and you have at least one other Apple device, get the new Apple TV 4K. There is little to not like about it. Even if you don’t have 4K, you’re future-proofed for a few years at least and the power of the A10X is nice.

The review goes through a few complaints, all relatively minor. Read it for details.

As to price:

The Apple TV 4K is an expensive streamer, for sure. A starting price of $179 is nothing to sneeze at. A 4K Roku can be had for less than that, and the very recent Amazon Fire HD box is even cheaper —assuming you tolerate the ads and data mining associated with the company.

But, a better way to look at is as an upgrade charge for your existing iTunes content, if you have any. The deal that Apple made with Hollywood to upgrade past HD purchases to 4K is unprecedented, and a great boon for consumers.

The Amazon Fire HD is $69.99. Add to that another $15 for an ethernet dongle if your WiFi is not up to the task of streaming 4K video. All in, $85. Compared to $179, that’s a huge difference.

If you already own iTunes content, the free 4K upgrade will make a difference. My personal experience with the Fire TV interface is that the Apple TV design is much friendlier, much easier to use.

If you are on the fence, I’d wait for a head to head comparison between the Apple TV 4K and the Amazon Fire TV 4K. The latter is due to ship on October 25th.