[…]Despite jumping through the deliberately disorienting hoops of its story, “Eternal Sunshine” has an emotional center, and that’s what makes it work. Although Joel and Clementine ping-pong through various stages of romance and reality, what remains constant is the human need for love and companionship, and the human compulsion to keep seeking it, despite all odds. It may also be true that Joel and Clementine, who seem to be such opposites (he is shy and compulsive, she is extroverted and even wild), might be a good match for each other, and so if they keep on meeting they will keep on falling in love, and Lacuna Inc. may have to be replaced with the Witness Protection Program.
For Jim Carrey, this is another successful attempt, like “The Truman Show” and the underrated “The Majestic,” to extend himself beyond screwball comedy. He has an everyman appeal, and here he dials down his natural energy to give us a man who is so lonely and needy that a fragment of memory is better than none at all. Kate Winslet is the right foil for him, exasperated by Joel’s peculiarities while paradoxically fond of them. The shenanigans back at Lacuna belong on a different level of reality, but even there, secrets are revealed that are oddly touching.
Kaufman’s mission seems to be the penetration of the human mind. His characters journeyed into the skull of John Malkovich, and there is a good possibility that two of them were inhabiting the same body in “Adaptation.” But both of those movies were about characters trying to achieve something outside themselves. The insight of “Eternal Sunshine” is that, at the end of the day, our memories are all we really have, and when they’re gone, we’re gone.
From the review by Roger Ebert