The film opens on a woman talking about someone: happily, most of us will realize that the person being talked about is Stephen Hawking. After all, the movie is titled after his most famous book. But Morris isn't going to tell you who anybody is: people talk, and you guess who they are. The effects are cheap crap and I rather wished they'd passed on them and just stuck with the people talking, but the effects aren't the point of the movie nor are they a huge distraction.
The people and stories chosen paint a fascinating picture of a brilliant but unfocused young man (something Hawking himself admits to) whose ideas and interests come sharply into focus because of his disease. Another piece of that puzzle was added by a colleague (?) who talked about how having to work almost entirely inside his own head (because reading and writing are so problematic for him) meant that Hawking had to develop a unique toolset - and when you have a toolset that no one else in the world has, you make unique discoveries.
A fascinating portrait of possibly the greatest genius of our age - worth a watch if you have the slightest interest in Stephen Hawking. Also a great companion piece to the wonderful "The Theory of Everything," a fictionalized version of his life.