I don't use it 24/7 but I do use it for extended periods of time when testing a product I work on. It's fine.
It's generally pretty fast, about what I'd expect if I was connecting to the box directly (which you technically are, I believe). Battery drain is probably a thing, but I honestly haven't noticed; my phone battery pretty much only needs a charge by nighttime, same as it was pre-tailscale.
