So this is some feedback I've had so far regarding the TestFlight for visionOS, but it also applies generally to both versions (both visionOS and Quest 3).

Seems like a great upgrade so far!

I love the interface and how the hand gestures work now, pretty straightforward to just tap and make the playback bar appear/disappear instead of the clap mechanic (which I remember you could turn off)
I love the UI and visual upgrades, that's nice! But I do wish there was a way to sort and use filters beyond just "top" "new" etc... (like 8k, 180, 360, ursa immersive, so on, similar to the categories...).
A big thing I'm missing is the ability to easily rotate the view in video -- maybe I'm just missing something? But it was nice to just tap and hold that recenter button and move my head/hand around to fit a more comfortable position
I love the new menu! It looks great and less cluttered than the last one. I wish I still had a quick way to change resolution, but I also don't mind since once you set it, it remembers for the most part. I wish maybe there was a youtube-esque setting in the menu to always choose either "Auto", "Highest Quality", or "Data Saver" or something like that. I think I'd just love a settings interface — I’m assuming you’re still working on that, but settings like before would be great, like passthrough settings, stereo settings, default streaming settings, etc.
Videos load much faster! This is my favorite upgrade of all, I'm so happy about this!! It feels like a lot of backend overhead weight was taken out or something because this is really fantastic.- I’d love a settings interface — I’m assuming you’re still working on that, but settings like before would be great, like passthrough settings, stereo settings, default streaming settings, etc.- Would love the ability to delete some ‘other websites’ instead of having them saved there, but that could even be in a settings menu (I feel like putting it close to the tabs up top might make for accidental clicks and frustration)

Vision Pro (M2) specifically:

There’s a bug where the video will not play at full fps unless the player bar is called. Once you get rid of it, fps drops noticeably.
The interface is pretty sleek, but i wish the keyboard was a little nicer? Idk how to explain that. It’s nice, but it could be polished up closer to the apple keyboard — or would be nice to just be able to use the default vision pro keyboard actually tbh