I was, at one time very recently, very deep in the VR/AR space. It seems to me that there will be quite a bit of time before people accept projectors pointed at their eyeballs (or however you want to explain Magic Leap's "digital light field" technology).
$800M on $4.33B post- is a big chunk of a company, particularly one that does not have a working product demo yet. Maybe it'll all shake out positively, but I am of the opinion that this is not real.
Lastly, all of Magic Leap's demos are very clearly not using wearable hardware (and also not being demonstrated using any kind of light-accurate reproduction). For example, metallic effects usually require "black" as a shade and things like the Lumus Optical lenses cannot reproduce such an effect (despite being basically the cutting edge of lightfield reproduction).
In short, I am bearish on Magic Leap.
Also, I am super confused as to why Magic Leap is operating their own silicon fab... That seems crazy to me.
Edit: Fixed the $'s from VC-land.