James MacMillan's new opera The Sacrifice and Rossini's La Cenerentola: they're as different as chalk and cheese. But as staged by Welsh National Opera at the New Theatre, they had two things in common: terrific singing from the WNO chorus, and alert, characterful playing from the WNO orchestra - ranging all the way from MacMillan's massive brass and percussion crescendos to Rossini's filigree flute ornamentations.

The Sacrifice took me back to the 1960s, and a hotel in Prague. Atmospherically recreated by Vicki Mortimer's set design, here was the hotel ballroom, with its cheap, chipped, wood veneer walls, and garish light fittings designed to look like molecular clusters. It all seemed very appropriate to the storyline, the tale of a blood feud between two families, which would hopefully be ended by an arranged marriage across the two warring factions, in an inversion of the Romeo and Juliet theme. In best soap opera fashion, the wedding ceremony goes disastrously wrong, and the seedy ballroom witnesses the first of several knifings and shootings.

Hurrah, WNO has at last introduced surtitles for operas sung in English, but in this case they weren't necessary, so well does MacMillan score for the voice, and so clear is Michael Symmons Roberts's libretto. The orchestral accompaniment (conducted in Oxford by the composer) is often filmic in character, rising to gun-shot, crashing crescendos that make you jump. In contrast, there are some quite schmaltzy arias: Your heart is my homeland, for example. Stage direction (Katie Mitchell) seemed to lack dramatic tension compared with the fireworks coming from the pit, but there was strong and confident singing from Lisa Milne as Sian, the girl who has been ordered to marry Mal (Peter Hoare, his voice trembling with pent-up rage), Leigh Melrose as Sian's real lover Evan, Sarah Tynan as Sian's sister, and Christopher Purves as Sian's father, shot dead by mistake. The Sacrifice creates a strong, immediate effect, but I wasn't left caring much about the people still alive at the end.

The dramatic action is also in danger of becoming overshadowed in Joan Font's quirky new production of Cenerentola. This time it's six giant rats drawing the attention. Look in any corner of Cinders's kitchen or the Prince's palace, and you see them scampering about, and drinking in every detail of what's going on, like ultra-nosey neighbours. With equally quirky, colourful designs from Joan Guillén, this is a panto-style Cenerentola, complete with broad-brush, cardboard characters.

Rossini's Cenerentola lacks the tension of the panto's glass slipper sequence in the second half - you don't have to saw off a foot to make a mere bracelet match the duplicate the Prince gives to his mysterious guest. This seemed to affect Marianna Pizzolato's Cinderella (pictured) - her beautifully warm, dark voice and characterisation trailed off towards the end. Also, with no slipper to fight over, the Ugly Sisters (Joanne Boag and Julianne Young) weren't vicious enough, leaving Robert Poulton and Earle Patriarco to enjoy a high old time as Magnifico and Dandini. But it's those rats I will remember.