Snap’s latest generation of augmented reality Spectacles have been lambasted by one of the engineers who helped to create them. The glasses, revealed earlier this week, were described as “a disaster” by Sterling Crispin, a former design engineer for Snap.

Bailenson and other Stanford researchers tested out the Meta Quest 3, a “mixed reality” headset that lets people blend physical and virtual worlds. While the headset is different from AR glasses, the gadget can display real-time video of a user’s surroundings in the physical world.