I like the three areas (learning, usability, game). Would it make sense under “usability” to break out something like ease of entry?

What I’m thinking of is “getting your bearings.” For example, I think Second Life is extremely difficult for someone who hasn’t been in other virtual worlds. Some of that’s from the open-endedness of SL (it doesn’t have a clear purpose, like a game would), but some of that’s from the complexity of learning to manage your appearance, control your movements, find out how to find things out, and so forth.