Musical theatre is often looked at as a ferocious and entertaining beast without a heart; a genre that provides plenty of flamboyant singing and dancing but very little substance. Every now and again, however, a show comes along that embodies the spirit, emotion and class that musical theatre holds in its overall promise, and Wicked is such a show.

Wicked’s pedigree internationally is without question: it’s a smash hit on Broadway, hugely successful in London and other overseas productions continue to do well. Its innocent shell – a prequel to the much-loved children’s tale The Wizard Of Oz – hides an even deeper interior, telling the extraordinary story of two young girls from backgrounds that couldn’t be any more different; both overcoming great challenges, and extraordinary hurdles. How these girls become friends, and then emerge as the Glinda The Good and The Wicked Witch Of The West, is an epic journey that is a full blown experience rather than a two hour joyflight.

Wicked’s spectacular costumes and contemporary staging are the real stars of the show, and the gasp of wonderment from the audience when Elphaba (Amanda Harrison) flies into the air at the spectacular conclusion to act one embodies the incredible connection this show builds with an audience throughout. And such gasps keep coming, whether it be at one of the many hundreds of wonderful outfits or the strong, action-packed script that has so many surprises along the way that it almost makes Wicked a show you need to see two or three times to really take it all in.

While Wicked’s overall package is unquestionably brilliant, there’s plenty of pressure on the principal cast to carry it over the line, particularly when it comes to the roles of Elphaba and Glinda, played in Australia by the durable Amanda Harrison and the perky, bubbly Lucy Durack. The show requires utter strength in these roles and a balancing act is also needed as one overshadowing the other can provide difficulties, particularly given there needs to be a considerable shift in pre-conceived ideas and notions throughout the show.

While both Harrison and Durack seemed vocally strained at times on opening night (in fact, there were cracks throughout the entire principal cast), the ingredients were all there to suggest that the duo will pack a powerful punch in the Australian production when things settle down.

Harrison makes a wonderful Elphaba, and while she doesn’t get it right early on with ‘The Wizard And I’, by the time she is mid-way through the second act performing ‘No Good Deed’, she has very much arrived. It’s a performance that builds and while I would prefer to see Elphaba a model of consistency throughout, Harrison certainly delivers the role the strength, charm and ultimate grunt it requires.

Durack owns the first act. From the moment she descends on the stage in a giant bubble through to her trademark number ‘Popular’, she has star written all over her. It’s a performance full of brilliant comic timing, strong acting and while, as mentioned earlier, her voice wasn’t perfect on opening night, as soon as she settles into the role Durack will very much deliver a near perfect performance – it’s on the verge of being that already and the way she brings the required ark of emotion (from the bubbles and squeak early on to the darker elements in the second act) is five star stuff.

By the time Harrison and Durack get to their emotional duet late in the show, ‘For Good’, the two witches have very much found the balance Wicked requires to ensure it reaches its conclusion as intended. The casting is spot on, it just needs a little more ironing out and probably two or three more weeks worth of performances before it is where it needs to be.

Rob Mills and Anthony Callea are both great as Fiyero and Boq respectively. Mills delivers ‘Dancing Through Life’ with plenty of joy and enthusiasm while Callea is a fun and engaging Boq, and his scenes with Penny McNamee (Nessarose) are wonderfully entertaining – a duo well and truly connected.

Rob Guest makes for a fine Wizard, though Maggie Kirkpatrick’s Madame Morrible needs a little more grunt and power to ensure the audience feel the right emotion towards the end of the show. The ensemble cast is solid, with its contemporary dancing a real highlight from the outset and at no stage does the show feel cramped as one may have feared at the Regent.

So often we look at shows and it’s easy to pinpoint errors and when they were made, whether it was in the casting room, the rehearsal process or the day-to-day performances themselves. Wicked, however, gets it so right. The casting is strong, the staging is wonderful, the direction and musical direction is spot on and as expected given its international success, the script is tight and punchy.

Squabbles are minor. As mentioned earlier, there’s some vocal issues to iron out, and at times the sound appears just a little too low, particularly in numbers like ‘Defying Gravity’ which should really rock the theatre - both orchestra and performer could do with pumping it up just a little there.

Wicked is a musical that pulls at the heartstrings, makes you laugh and fills you with a sense of excitement all at the same time. It reminds you of your closest friendship, your darkest times, the fun and frivolity of life and the importance of the choices we make, and those made for us.

This is the best production of a mainstage musical Australia has seen in decades, and it has all the promise of a show that should run for years.

A must-see, go-back-again extravaganza.