It seems a pity to have to mention Corella Ballet at this point. Their four-part performance at Gaillard Auditorium Sunday was worth a dozen hyperbolic superlatives. In the audience, a mother sat nearby me with her 13-year-old son, a seemingly normal 7th-grader. “I can’t believe you made me come to this,” he complained before the show began. “Ballet is for girls. This is stupid.” During the final piece, the mesmerizing DGV: Danse a Grand Vitesse, I snuck a peek at him. He sat riveted, slack-jawed, eyes wide, PS3 hanging abandoned and forgotten at his side. Lemon Anderson, the producer and solo star of County of Kings, was also in the audience and tweeting during one of the two intermissions. “Magnifique,” he pronounced it. You know you’ve got a class act when you can prompt a prison-hardened hip-hop artist to break into French.

These 28 sleek Spanish dancers made hummingbirds seem like bumbling galoots. Housecats wept openly in their presence. The Roman god Mercury was seen flagellating himself in the shrubbery behind the Gaillard afterward. Angels lit their own wings on fire and sawed off their feet. Corella Ballet came, tossed off three unforgettable performances, and then swept out of town before the weekend had even had a chance to catch its breath. For three short days, the most commonly heard phrase around town was, “I’m not really a ballet person, but…” To speak of them now seems like schadenfreude, mere spite. Best to forget I mentioned it and try to think about something else.

Last night’s world premiere of Émilie, from Finnish composer Kaija Saariaho, who knows a thing or two about contemporary opera, was one of the festival’s big events. Anticipation at the Memminger Auditorium was electric, urged on by a spate of brief sneak previews last week and glimpses of the visually striking set. Indeed, the set alone fired the imaginations of audience members on entering: a sloped jumble of interlocking platforms, like the breakup of a black ice floe, over which hovered a bizarre geometry of translucent white quadrilateral scrims, which for those of us in the audience burdened by not-so-fond memories of high-school geometry were an immediate visual reminder of our inadequacy in that department, and had some commentators wondering if they were about to be subjected to an artistic rendering of the SAT.

Some of them were still wondering when it was all said and done. The artistic worth and enjoyability of what transpired for the intervening 75 minutes is open to debate. By some accounts, Émilie was transcendent – musically, lyrically, visually. By other, perhaps more common, accounts, the only drama to be seen Sunday night was in the opera’s dramatic failure to live up to the expectations it had set for itself. As often happens, opinions often broke according to the holder’s affinity for opera to begin with. “I hate opera. And math,” one friend tweeted in mid-show. Others were not so kind.

There’s little argument that it was awfully nice to look at. Director Marianne Weems and video designer Austin Switser used the floating parallelograms to wonderful effect, projecting on them video and images that gave depth and texture to the libretto (of which it could use all it could get): candles, mathematical formulas, a hand scratching out letters with a quill or circles with an ancient drafting compass, flames, splendid images of the sun roiling with coronal eruptions, even an ultrasound of a squirming fetus at one point. Saariaho’s score, deftly conducted by John Kennedy, also garnered lavish praise from most comers. And soprano Elizabeth Futral, who played the central — and only — character in the work, Émilie de Chatalet, wrung everything she could out of having the exotic stage all to herself for over an hour – any performer’s dream come true.

Most critiques seemed to be variations on the opinion that the libretto wasn’t really about anything at all, lacking conflict, character development, or poetry, being mainly a lengthy complaint about being ignored by her lover, Mssr. Saint Lambert, and the kind of stuff one would hear in a high school science class: “The sun attracts the celestial bodies toward it because of its larger mass,” Futral intoned, in a typical example.

A pair of young Festival Orchestra musicians, walking home after the performance, were asked whether they enjoyed the opera. “I’m not sure ‘enjoyed’ is the right word,” one responded tersely. “It’s weird,” said the other. “But it kind of grows on you.”