BIG, green and very, very loud - the Americans have taken the beloved pantomime to a whole new level with the opening of the new West End blockbuster Wicked.

The musical adaptation of the prequel to the classic The Wonderful Wizard of OZ is chock-a-bloc with special effects, magical costumes, soaring sing-a-longs and witty in-jokes.

But if you're no Oz fan, or a schoolgirl, don't be put off, because Idina Menzel's Tony Award-winning performance as Elphaba, The Wicked Witch of the West, is quite simply spellbinding.

Before Menzel had even sung a note, the audience burst into applause at the mere sight of the green-faced star and when the musical stumbles over sickly-sweet moral lessons the anticipation of her next power ballad is enough to keep interest levels up over the two and half hours.

The musical tells the untold story of the early life of The Wicked Witch and her counter-part, Glinda, The Good Witch, played by Helen Dallimore, before Dorothy and her Tin Man et al take their famed walk up the Yellow Brick Road.

The spectacle starts with the inhabitants of Oz celebrating Elphaba's watery death, until someone points out that the two rival witches had once been friends.

The stage, adorned with cogs, lifts and a steel dragon, soon transforms into Hogwarts-like school, complete with a goat taking the history class.

Dallimore is extremely funny as the bubble blonde Glinda, with plenty of squeaky lines such as "It's good to see me, isn't it?"

While Menzel's deep-thinking, but lonely Elphaba is an instant hero.

Unfortunately the magic tricks are seriously lacking and I was left wanting some more Harry Potter-esq moments as the two witches explore their "gift".

Instead, the plot follows Glinda's pursuit of the charming Fivero, performed by the likeable Adam Garcia, and Elphaba's transformation into an animal rights activist.

Neither are particularly compelling and when Nigel Planer's Wizard of Oz is finally revealed it's disappointing and anything but wonderful.

The line between good and evil never really blurs and it's all too easy to cheer for the outcast hero, without ever having to question her actions or the motives of her rivals.

So if you're aged over 12, don't hope for anything too thought-provoking and just allow yourself to be swept away by this technically brilliant production.