He lived a long life, less than a year short of 90, and had largely said his piece in terms of the cinema; his last movie, the excellent Fanny and Alexander, was finished 25 years ago, and since then he'd confined himself to stage and television work. I have no doubt that stuff was excellent, but it was also next to impossible for an American to see, so I've been talking about Bergman the filmmaker in the past tense for my entire adult life. It shouldn't feel like such a loss that the guy is gone, but it does.
His keen visual sensibility, uncanny ability to handle actors, compelling (if gloomy) tone, and restless, unsweetened humanism shone through in everything he ever did. He made at least ten movies that have the potential to be life-changing experiences, and if you've never done so, rush to your local video store or Netflix queue and do yourself a favor by getting Fanny and Alexander, Scenes from a Marriage, Cries and Whispers, Shame, Through a Glass Darkly, Smiles of a Summer Night, The Seventh Seal, Wild Strawberries, The Virgin Spring, or, especially, Persona.
Pretty much no matter how you define greatness, he was one of the very greatest filmmakers in movie history, and he'll be missed.