There aren't many who dance so effortlessly and with so much pleasure they make you smile. Martine van Hamel is one of those few, and her warm, unaffected and beautifully danced Princess Aurora Friday night at the Kennedy Center Opera House brought fresh air and sunshine to American Ballet Theatre's cynical, dark and ornate production of "The Sleeping Beauty."

Technically, everything was there -- phrasing, musicality and a lithe power; a solid Rose Adagio and beautifully expressive arms in the third-act solo were among the many treasures. But van Hamel's contribution to the ballet went far beyond technique. More importantly, she was lovable. She ran on, a teen-aged Princess full of energy and life and promise, ignored the darkness and ennui surrounding her, and simply began to toss off the most difficult classical steps as if they were play.

There was a lot of good dancing in the five weekend performances of this choreographically sound production of the most complex Russian classic, but not a whole lot of love. Maybe it's just that the dancers are tired -- we're getting them at the end of a long season this year -- or maybe Nicholas Georgiadis' sour colors and ponderous sets have gotten to them, but one gets the feeling the dancers don't really like "Beauty" very much.

There are many aspects of the ballet, from uneven tempi to directorial details, that are still unsettled, which is to be expected. But the casting should settle down, too. There have been so many casts, so many dancers who have three or four solo parts in addition to their corps work, that it would be a miracle if they weren't confused and a bit perfunctory. It's as though the company thinks of the ballet as a collection of "numbers" rather than a story with distinct roles. If one has to be a fairy, an Aurora's friend, a courtier and a cat at the same performance, it's no wonder an "If it's Tuesday I must be the Bluebird" attitude has set in.

Because the dancers are tackling so many roles simultaneously, the changes from performance to performance have been enormous. Almost everyone has been measurably better in his or her second crack at a role. Van Hamel's Prince, Robert Hill, was so much more relaxed at their Sunday matinee performance he seemed a different man. Sunday, he danced the brooding, anachronistic solo Kenneth MacMillan has inserted for the Prince in the second act with landings and line as smooth as soft leather; his virtuosic third-act solo, all power and stretch, was both princely and passionate. What will he be like 10 performances from now?

Amanda McKerrow was another dancer who seemed transformed at a second performance. Her Aurora Saturday night, when she was partnered by Ross Stretton, was more confident than it had been two nights before, and her calm, cleanly phrased dancing quite beautiful.

The third Aurora, Cheryl Yeager (at the Saturday matinee), danced beautifully, too, but on such a small scale it's hard to imagine that this musical and lightweight dancer -- a perfect Princess Florine or Songbird Fairy -- will ever be an ideal Aurora. Her Prince, Julio Bocca, only 20 and galloping through the repertory this season in new role after new role, is another matter. A New World Prince for this very New World production, he kept a low profile in the second act (the macho strut he brought to "Etudes" might be useful here), though his dancing, particularly the footwork in the character dances, was excellent. In the third-act solo he tore into the turning jumps with an almost savage energy, but there's a polish over the fire that makes him interesting as well as exciting.

In supporting roles, Deirdre Carberry and John Gardner were the best of the Bluebirds, their dancing (her solo is full of turns, his is a compendium of leaps and beats) truly soared. Gil Boggs, in his second attempt at the role on Sunday afternoon, maintained the shape of the jumps more clearly than anyone, though he overshot a landing. Saturday night, Bonnie Moore and Robert Wallace (his was a debut) showed promise in this difficult, virtuosic work. She was a bit tentative; he had more bounce than finesse. Moore had been delectable as the Diamond fairy that afternoon, dancing with Wes Chapman (another debut), whose affable style and easy technique made his solo look less quirky.

No one has quite gotten the Lilac Fairy yet, unless you liked Leslie Browne's glamorously icy portrayal. Jennet Zerbe was the warmest, Carla Stallings the most regal. Victor Barbee was a bitter Carabosse Friday evening; Clark Tippet, a monstrously evil one. This production is almost a chess game between Lilac and Carabosse (who's played here as a James Bond movie villainess), a conceit which, though intellectually interesting, adds to its distance and coldness.