Take the time to at least start each composer's story, since the author changes approach and to a certain extent the affordances with each one (there's an especially nice interactive bit in Schoenberg). Overall I enjoyed the journalistic style though I felt Berg's part was too clever for its own good.
It looked great on mobile (Android Chrome) as well. Let's hear it for Twine nonfiction!
I originally rated this a 3 but considering the sum of its parts I think the 4 is well deserved.