It's a nice little bonus mode. Nothing substantial, though. You fight 15 waves of enemies, then you get to upload your highscore. Unfortunately the tiny map never changes. Don't expect any bosses, either. It's a fairly speedy game, by the way, so it might wreak havoc on the player's stomach. Mechanically it's really good, at least. Using your head movement for aiming feels great.
The regular old Stardust can be played in VR as well, of course, but it really doesn't add much. On the contrary, with the game being as visually busy as it is, playing it on a pin sharp flat panel display feels a lot more natural.