All Is Lost is just Robert Redford and his boat, period.
Even more than Spencer Tracy in The Old Man and the Sea, it's one man against the forces of nature.
Oddly enough, there are seven names credited with working on the dialogue, which is more than one man per sentence, and all the sentences are voiceovers before the movie proper really begins. Redford does not indulge in prayer or meditation, there is no narration, there is no thought track, and above all, there are no flashbacks. Just a lone man trying to stay alive.
The only thing I can think of to compare it to is Eddie Rickenbacker and some others who had to survive on life rafts during wartime, and nobody made movies about them.
But its very simplicity makes All Is Lost hard to review, because almost anything I say about the story will act as a spoiler and I don't want to ruin the suspense, which is considerable.
Let's just leave it that we never learn much about the protagonist except that he's strong and resilient and skilled in electronics, resourceful and inventive and not willing to indulge in despair or emotion of any kind, and he's imaginative whenever imagination helps. I don't know him well enough to like him, but I admire what I can see of him.
Writer-director J.C. Chandor does not indulge in fancy camera work except for a few underwater shots, most of which illustrate the indifference and menaces of the sea. Everything is businesslike and devoted to the story. There's not even much musical score.
All Is Lost is unusual, believable, exciting and suspenseful-- a movie for grownups who want something new.