I tried it a few months back, it's OK at Venom & Flash speeds.
In 3D the other craft can seem like cardboard cutout's/pop-up book sort of effect [all the PS3 3D games look like that IMHO], but the frame rate is halved to 30fps which is the real problem, that frame rate drop makes the game seem jerky compared to the smoothness of HD normally.
I play in cockpit view, so what I experienced might be different to somebody who plays in near or far view, and apparently everybody see's 3D differently, some not at all.

It's a novelty, but I don't think you could do any long sessions of more than 1-1.5 hours playing HD in 3D without getting a headache