Usability analysis involves carefully describing user interactions with a product, critiquing the product, and then proposing suggestions for improvement. Some folks make a living doing just this sort of thing.
You will be asked to do this type of analysis in the human-use assignment. In preparation for the assignment and the class on designing for human use, please read the PVR interface analysis document. This analysis is much longer that what you will be asked to do, but it will help put you in a human-use analysis mind set.