One thing that I really liked was the "discoverability" of the user interface.

I started to walk around, picking things up. Then, I noticed a little "i" on the bottom left. I typed "i", and it opened the inventory. Very good!

Now, the "i" was replaced by an "x". I really expected that "x" would close the inventory... but it didn't. :-(

Unless the "x" letter is reserved for something important, it would be nice if it could be used to close dialogs!