I don't have a Vision Pro (would love to try it for a while, but can't justify $3500 on something that is really just an early preview / technology demonstrator for future products). I do have a Quest. Admittedly I only really use it for VR games and 3D movies, but as far as those go it's an extremely impressive device for the $300 or so it costs. There's no better way to watch a 3D movie (like Avatar 2): even compared to when I saw it on a state-of-the-art dual laser HDR Dolby Cinema, it's miles better on a headset.
My Quest doesn't support using it as a monitor, but running its own internal apps (web browser, movie player, etc) shows me what the potential would be. You don't just get a monitor: you get an extremely huge, high-res monitor that is far more portable and practical than a real monitor of that size would be. Multiple monitors, in fact, if you want.
This is no longer true with recent Vision OS versions. You can pair input devices (physical keyboards, trackpads, etc) directly with the Vision Pro.
But I'd argue that its ability to work on gestures alone is actually a huge advantage: the Quest has those little puck controllers that you hold in your hand. They work fine but they're kind of a pain to have to pick up, carry around, change their batteries, etc. I've often just wished I could just use my hands as the controller, which of course is exactly how Vision Pro works.