Barring any disasters, a playable demo will be released on Friday.
It will contain 1 level, 3 new weapons (not fully implemented, but usable), and several new materials. Expect maybe 5-10 minutes of gameplay.
As for the weapons, one will be missing only the model, one is missing a model and a special effect, and one is missing an alt fire, but has a model. All of them are still fully servicable, and all that is left are aesthetics.