Unlike Day-Lewis, Redmayne portrays a man who gradually becomes immobilized by his disease. Like Day-Lewis, Redmayne avoids going for mawkish sympathy from the viewer. Felicity Jones is excellent as Hawking's first wife -- as Jane Hawking, Jones may actually be on-screen more than Redmayne. She makes Jane brave and sympathetic, more sympathetic than Stephen by the end (the movie is based on one of her memoirs, after all).
The movie's relatively faithful to reality, with the requisite condensing and conflating of events. The direction is competent, workman-like. When it strives for the cosmological sublime, it looks like a Discovery Channel show on space-time that's been stripped of Morgan Freeman's narration. Brief explanations of Hawking's importance to physics occur throughout, accurate though truncated.
Hawking's atheism (counterpointed throughout with Jane's devout Roman Catholicism) isn't addressed honestly, though, or accurately in relation to his best-selling A Brief History of Time. The movie makes that non-fiction work in which Hawking posits a model of the universe that he explicitly states leaves God nothing to do as a love letter about faith to his wife, by omitting the whole 'nothing to do' thing from discussion and instead focusing on Hawking's metaphoric bit about "reading the mind of God" as if it were literal.
Titles to keep the viewer aware of when things happen would have been nice, especially as the make-up people seem to have forgotten to age Felicity Jones over the 30 year span of the film's events. And the first half of the movie, which deals with the first two years or so of Hawking's ALS and marriage, is far stronger dramatically than the increasingly montage-like later scenes, as we rush through three decades like a careening space probe being sucked into a black hole. Recommended.