In her 50 years on earth, Madonna has carried off pretty much every look, even wearing bras that left her nipples poking out. But, just as some people don't suit smoking, so does Madonna look a bit of a ninny holding a guitar. This wouldn't be a problem if she didn't spend more than a quarter of her two-hour live extravaganza with plectrum in hand.

At first, it's a good gag seeing the first lady of pop inexpertly brandishing an axe. Her Grade One chords work a treat on a grungey version of Borderline. But as the set wears on, and she plays her way through some of her greatest pop songs - even Ray of Light - you long for Mark E Smith to come on and unplug her amp.

When she sticks to singing and dancing, Madonna is peerless. Vogue, which is mixed with the Tick Tocks of her latest hit, 4 Minutes, is a thrill. As is Into the Groove, which features a fearsomely complicated skipping sequence and a brilliant bit where Madonna knocks her dancers over like dominoes. Better still is a Gypsy-folk version of La Isla Bonita, which suggests Madonna picked up some tricks from Gogol Bordello's Eugene Hütz. A ravey take on Like a Prayer provides the biggest dance-along of the evening; You Must Love Me, from Evita, the most sobs.

Near the end, there is some excitement when Madonna suggests she is about to take requests, and starts an a cappella version of Express Yourself. But, like in the Beijing Olympics opening ceremony, there is no room for spontaneity here. As if reading from an autocue, she breaks it off and woodenly declares: "Stop that shit. I'm in charge. I choose the songs." And strums her guitar again.