I've sent my 830 back because of the "bad" display and ordered the phone from a different store.
The new phone arrived yesterday, and of course I checked the display immediately.
While viewing angles are definitely better than with the first 830, they're still nowhere near as good as with my old L920.
This isn't really a problem during the day, really, but at night when it's dark, the whole display (even the black parts) glow visibly.
Maybe it just needs some getting used to, I don't know.
I've been waiting so long for the L830, and it is an awesome phone otherwise, so I guess I'm gonna keep this one.
Still, display-wise it seems a bit like a downgrade :/