It gave me angry disc errors just like the last disc I used, and just about as many times before randomly deciding to work just fine. I guess the laser mechanism is just on its way out. Not surprising, I guess.
I managed to get it to initialize the disc by pressing the Initialize button, holding it screen-up, and then just as it started the initializing, turning it 90°. That seemed to jostle something in just the right way that it immediately initialized without any issues and now works just like the last disc I used, just with a lower capacity.