Question about the Bullet physics integration.

I can no longer use JBullet, as I rely heavily on GImpact and its not stable in it. I need to switch to a new physics implementation, and I saw that LWJGL3 now has Bullet Physics. Is it complete & stable?

It's complete, but slightly out-of-date. However, the bindings are not released or officially supported yet, because we're currently investigating alternative physics solutions. See #428 for details.