It's really too bad that they haven't rolled this out for 1080p too. Their 1080p video quality is god-awful compared to Amazon. They may even have made it worse: from the "ladder" comparisons, it looks like they jump to higher resolutions at lower average bitrates now, so if you're stuck at 1080p you're going to be getting worse quality after these changes than before.

Also, something that's kind of weird about all this is that encoders (x264, x265, etc) already have their own rate control algorithms that decide on a frame or scene basis how many bits to use. Netflix taking an approach like this is equivalent to claiming that they're capable of doing a better job than these codecs in an automated way - so why not just contribute the code needed to achieve these improvements back to the projects they're using?

Last, it's very weird to select individual frames from an encode and not a selection of frames. The comparisons purport to show that the lower bitrate encode is better than the higher bitrate encode, but in fact (if I understand how they're using rate control correctly) what they are showing is a single frame in the lower bitrate encode that uses more bits than the same frame in the higher bitrate encode. So it's arguably not a fair comparison. And even with that, depending on how sensitive you are to artifacts, some of the "optimized ladder" encodes still look worse.

Edit: here is an example of what I mean when I said that they may have made the quality at 1080p worse. If what you end up watching is the highest bitrate 1080p available, you would get higher quality on the old latter than on the newer one. https://i.imgur.com/rzPR7Sh.jpg Actually, on some of the examples, even 720p on the older ladder is better than 1080p on the newer one!