The great and good of the London music scene were gathered at English National Opera last night for the unveiling of American Wunderkind Nico Muhly’s new opera, Marnie. Although it was commissioned by the Met in New York, somehow ENO managed to wangle the world premiere, which has been widely hyped and was ecstatically received by a packed house. But for all that there was much to enjoy, it hardly deserved such rapture, and there were problems with both piece and production.

If the best is the enemy of the good, then the excellent is also the enemy of the "meh". And if you can stomach Verdi's Aida, go and see English National Opera’s new production for its central performance by Latonia Moore.

“Then I’ll kiss her so she’ll know.” At the sound of his ringing voice, the girls part to reveal him standing there, a hapless monument of rumpled charm. The audience relaxes in pleasure as an easeful actor joyfully shows what you can do with a command of textual detail, physicality and, above all, character. The trouble is, the excellent Gavin Spokes is playing not one of the leads but the supporting role of Mr Snow. The downside of a performance this assured is that it shows you exactly what has been missing until now.

It's time again for surrealist charades at the nothing-doing mansion. Christopher Alden's Handel is back at ENO, making inconsequentiality seem wondrous. Christian Curnyn's conducting sets the tone, with orchestral playing as light as air, and a new cast – with one singer from the previous set switching roles – conceals its art behind what seems like the easiest and most organic of singing and acting.

After a Royal Opera performance of Birtwistle's The Minotaur, a friend spotted Hans Werner Henze in the foyer and had the temerity to ask that annoying question "What did you think?" "Very competent and extremely well performed," came the reply. Which is the measure of Ryan Wigglesworth's Shakespeare adaptation at ENO.

In the annals of ballet directors, always searching for the perfect balance between heritage programming and new work, there can rarely have been a double whammy so successful. In pairing a brand new Akram Khan Giselle with Mary Skeaping's near-perfect 1971 production in one season, English National Ballet may be setting an Orwellian future against a Romantic past, contemporary dance against the most classical ballet, but they have no jarring contrast on their hands.

It should have been unmodified rapture: a gathering of English National Opera team members old and new celebrating the doyen of the company's best-selling productions. And, as has always happened with the artistic side of the company, this loving homage to Sir Jonathan Miller sounds like a triumph. Critics weren't invited to the gala - statement, not sour grapes; this was a charity event, after all - and the final rehearsal was closed, though not apparently at the wish of anyone performing. The circumstances, though, tell us a lot about a company divided.

After a day of sheer pain, would it be endless night or cathartic relief at ENO? Both, must be the answer, and much more, all at once. Iconoclastic Frank Wedekind's "earth-spirit" Lulu, exploited as a street-child but now able to turn the tables for a while on male bourgeois weakness, lives through one horrible situation after another before dying at the hands of Jack the Ripper, but Alban Berg's never merely atonal score gives such transcendent warmth to the spell she casts just by being.

No-one can easily replace Mark Wigglesworth as Music Director of English National Opera: ask any of the musicians working there and you'll find they're all heartbroken. That said, they could not have chosen a nicer man or a better all-round musician than Martyn Brabbins.

Pace-perfect musical articulation and meaningful surprises in the direction: both were to be expected after the conductor-generated sludge and the production overkill of the new Royal Opera Così fan tutte. Mark Wigglesworth has form in Mozart at ENO, with the best of Cosìs way back and a bewitching revival of The Magic Flute this year. Last night he and the ENO Orchestra put no foot wrong. Richard Jones, his dream first-time collaborator, offered the expected twists and symmetries though perhaps not all the connections in between.