I just set mine up an hour ago, so here are a few first impressions/observations:
It is fast.
You can go to the Play Store and load YouTube TV, CBS All Access, etc. BUT, there is no integration that I've found with the Tivo Stream App.
Disney+ is integrated with the Tivo Stream App, but when I search for any Disney+ movies, the Tivo Stream App finds it, but shows it is available on Prime Video only. I tried 3 different Disney movies that I know are on Disney+, and none of them showed up as available on Disney+.
I use YouTube TV (not Sling), so I am disappointed in the "Tivo Stream App" itself. The guide has nothing but the crap channels from Tivo's channel (its a lot like Pluto TV). The only use I"ve found for the app so far is to search for tv shows I like and adding them to "My Shows" and then I can watch them on any service instead of having to search each app. I'm still playing with this, so opinions WILL change as I play with it.
On the main screen, I like that it lists all the apps across the top where I can go directly to Netflix, or YouTube TV or whatever. THEN, scrolling down, it has each of those same apps listed on the left side of the screen and content from that app/service listed out to the right. SO....I can move down to YouTube TV and look to the right of the logo and it shows me "ESPN", "CNN", "NBC5", etc. You click on CNN and it goes straight to CNN on YouTube TV! On Disney+, it has a ton of the movies (there is one line for recommendations and another line for watchlist) showing. You click on the movie, and it goes straight to that movie.
The remote feels really great.
The search function has been very sluggish a few times, and blazing fast other times.
Tivo Stream App crashed twice when going to it from main screen.
Picture quality for some reason is better on the Tivo Stream 4K than my Xbox One on the YouTube TV app.
So, there you go guys. Disappointed in the "Unified Guide" since I don't have SlingTV. I really wish they would have partnered with YouTube TV instead since they give unlimited cloud DVR. I'll add more if something big comes up. I am now on my way upstairs to install one of these on my wifes TV in the bedroom. BTW, setup is very easy. I hope everyone gets theirs soon!