It appears to be an aggregation service. Instead of individually searching across N platforms for content (hulu, disney+, youtube, crunchyroll, netflix, etc), you can now just use a single app (Google TV) which will allows you to search and stream across all platforms you are subscribed to.
Furthermore you can cast stuff directly to chromecast from Google TV as well as watch locally on your device.
(I genuinely thought it was still called Google TV so I was rather confused by this post - I couldn't work out what was new.)
The only aggregation on existing Android TV seems to be “Continue Watching” across apps.
The idea is sound: Let's use a common interface to all the content offered by the apps you already have installed.
But in practice (on Apple at least), it's awful. There's no telling whether you'll actually be able to view the content you see, or if it's just going to lead to some screen where you need to buy the content individually. Want to watch Family Guy? Oh it turns out YouTubeTV (your TV provider) has it but it's not donated to the AppleTV app, so you get a purchase link to buy an episode for $5, even though YouTubeTV actually has the same episode in your DVR library.
Want to watch the $sportsteam game that's on? Oh there's a link right there to watch it in the $sports_app app! Except that link takes you to a page that explains that you don't have the subscription necessary to actually watch the game. Or oops, it's blacked out in your area.
Or maybe you finally select something that's actually available to watch, so it links you out to the app that contains that content, only to have the app fail to support the appropriate intent/deep link, so you just end up on that app's home screen.
It ends up being this very hit-or-miss experience where anything you want to watch has like a 70% chance of actually succeeding, so you don't trust it, and it ends up being worthless.
Yes I'm bitter.
Why should like me get such aggregation services that require 4 different subscriptions that add up to 600 Euro per year?
I never got these aggregation services - and there are already MANY of them. Here in Germany the Telcos are having setup boxes that are more powerful than this Google TV thing as they aggregate subscriptions AND are able to stream live TV via Cable. Just google Magenta TV and GIGA TV.
I have no issues with Amazon (or Netflix, which I don't use) knowing what I stream, but I do have an issue with Vodafone or Telekom knowing which TV channels I'm watching at what time.
That's why I prefer DVB-C.