One of the facets of the brilliance of Shakespeare is that there are no simple solutions.  His plays, like life, are complicated and the results, more often than not, are less than ideal.  What joy one should take in the happy resolutions of his comedies, and what warning should one should take in the dark explorations of the tragedies.  King Lear, if not his masterpiece, is one of his best. The exposition of Lear's temperament (in our day, we might call it his descent into senility, the loss of his rational mind) is moving -- having glimpses of understanding what he's done to his best and youngest, it breaks his heart. As others have noted, the ending of the play is not without redemption, as at least one of the good guys, Edgar, survives.  But not all the guilty are punished, and not all the innocent are free. That's the hard nature of tragedy.

Well, of course, it depends upon your meaning of "unsatisfactory." Do you mean unsatisfactory because you don't like it? Do you mean unsatisfactory because it violates the preceding structure and logic of the play? Do mean unsatisfactory because it does not seem realistic to you? There are many ways in which unsatisfactory may be construed. As an example of one, it may be argued that the ending of another work, The English Patient, is unsatisfactory because it violates the preceding structure and logic of the novel. In King Lear, the ending may be viewed as satisfactory because it is realistic and fits the preceding structure and logic of the play. It may viewed as unsatisfactory because it is painfully sad and represents unpleasant ironical injustice in life.

I personally think that the ending of this tragedy represents one of the most powerful endings in drama as a whole, not just in Shakespeare's plays. The unyielding bleakness of the image of a deluded Lear, clutching his dead daughter in his arms is one that should make every audience severely question the whole concept of justice and the way that often innocents are punished for the sins of others. As such, the ending is perfectly in keeping with the themes of this play.

The ending of the play is very powerful, making it one of the most thoroughly tragic of all tragedies. The ending may not be morally satisfactory, but life is often not morally satisfactory, either. Shakespeare seems to have known what he was doing, artistically, by ending the play as he did. This is one of the darkest tragedies in all of literature, and it is appropriate that it should end darkly as well.

Being an individual that appreciates situations where people get what they deserve, I find the end of the play unsatisfactory because there is no reason that Cordelia should die—her father should never and exiled her in the first place. She was the only one of his daughters who was honest with him: however, he did not want to hear honesty...he wanted someone to stroke his ego—which his other daughters, who care not a wit for him, do. His actions not only lead to his own downfall, but place Cordelia in circumstances which bring about her death. This is a tragedy, and so Cordelia's death can be no surprise, but in terms of the story, the tragic end (as with Hamlet, Romeo and Juliet) does leave me feeling unsatisfied. However, perhaps many tragedies do because things generally cannot be worked out to our satisfaction—at least in terms of "fair play." (On the other hand, in Macbeth—for instance—Macbeth is a tyrant who has murdered many innocents, and his death seems justified.)