A lot of things. You're always in the sweet spot of viewing. Little to no cross talk as you've mentioned. The depth is better, IMO. At least for me, yes, it does appear to have more realistic depth than viewing on a TV. Adjustable size of the "movie screen" allows you to feel like you're seeing it on a REALLY large screen (limited to an extent by the FOV of your headset).
Speaking of adjustability, depending on the viewing app, you can manually adjust a LOT of settings WRT how the 3D media is presented. The virtual screen can be moved "closer" or "farther" from your eyes in addition to how large the virtual screen is. You can adjust the separation and thus tweak the "depth" of the 3D, really handy if your IPD isn't exactly the same as what they used when filming the source media. That last is helpful for me as my IPD doesn't fall within "standard" range. And again, depending on the app, you can even make the virtual large screen "curved" versus being a flat virtual screen.
One of my favorite features is you can even pick the setting where the screen is. My favorites depending on mood are "Drive In Theater", "Movie Theater", no setting. I like the Drive In Theater one a lot as it reminds me of when I was younger and used to go to Drive In Theaters with my family and later on with dates.
It's amazing how your perception of how large the screen is can change depending on what setting you choose to set the virtual screen in.
A little weird at first, but it's kind of nice to be able to die down on my back in bed to watch a movie. I guess you could achieve something similar with a projector aimed at your ceiling.
But it's an incredibly relaxing way to watch a movie, IMO.
I'm sure there's other things I'm not thinking of at the moment, but it's been a few months since I last watched a 3D movie.
It's obviously not VR, but at least for me, the 3D is much better on the Quest than it is on a TV.
The main drawback for me is the FOV.
Yeah, the Rift CV1 has a similar resolution to the PSVR and that was more of a trade-off versus a TV capable of 3D playback (low resolution, very obvious and large pixels combined with the screen door effect). The Quest has much better resolution (still needs to be better) which leads to a significantly better media viewing experience. PSVR 2 should be even better, assuming it has a good media viewing app with multiple settings to control how the media is presented and rendered.
Regards,
SB