The movie does an excellent job of showing us that, and also of setting up the character's life, and what would happen after he returns home. It is a drama, but it's not something designed to upset the viewer. Everything is done right: the editing, the soundtrack, the camera shots, the sets, the costumes, the accessories, the scenario, the dialogs, and the story.
Tom Hanks is perfect, a high note in his career, without a doubt. He brings excellent dramatic emotions to the screen, as well as incredible poise in the loneliness of his character and his defeated look, not to mention going to incredible dietary length to get really emaciated.
The only negative things I've found, are not that noticeable. First, the Christmas family dinner is a bit over done in true Hollywood fashion. Second, the "sea" during the crash is obviously set in a large artificial basin and the huge waves are CG. Third, the night time scenes on the island don't look real.
That being said, it's a must see.