Gilberto Gil, Barbican, London <!-- none onestar threestar fourstar fivestar -->

"Today, I'm 64," Gilberto Gil announces, then he launches into The Beatles' "When I'm 64" with evident delight. Now I may seem mean by stating that I grimaced as Paul McCartney's sentimental opus was sung to a samba-reggae beat, but Gil had already delivered a bossa-nova treatment of Lennon's "Imagine" so this encore felt too much.

Which is a pity, as Gil is one of the planet's truly inspired musicians. It just depends which Gil turns up. And, at the Barbican, we got the prog-rockin', jazz-funkin', karaoke-singin' Gil. That the largely Brazilian audience lapped it all up, dancing in the aisles, singles me out perhaps as the party-pooper. But, really, this was pretty awful.

I feel bad saying that. And it's not often critics feel humbled by dishing out lousy reviews. But Gilberto Gil is someone you want to like. Gil is Brazil's most iconic musician, rewriting Brazilian music's rule book in 1967 after hearing The Beatles' "Strawberry Fields Forever" on the radio while, simultaneously, a band playing north-east Brazilian folk music wandered past.

Intent on merging these two seemingly disparate music forms, he helped launch the Tropicalia movement. With their hippie clothing and unorthodox music, the Tropicalistas outraged Brazil's then military rulers and both Gil and fellow performer Caetano Veloso were arrested, incarcerated and forced into a two-year London exile.

The Barbican's Tropicalia Festival (April to May 2006) was thus a celebration of a moment in Brazilian culture when the arts were galvanised by social change. Gil, the pioneering Topicalista, missed the event but the World Cup - he recently played in Germany - has brought him back to Europe. Finally, the Tropicalia Festival has closure. But what kind of closure?

The Gil who offered psychedelia a Latin flavour and encouraged Brazil's black populace to respect their African roots was not evident. Instead, we got a sprightly musician dressed in white who began with Genesis-style prog-rock, let his five-piece band drift into bland jazz funk, sang Bob Marley hits and appeared happy to soak up as much adulation as possible.

Beyond two artfully chilled bossa nova numbers and a samba football song, the Barbican concert was Brazil-lite. The genre-bending musician who recently, employed north-eastern Brazil's foro folk music to great effect was not in the house. Considering Gil also has a day job as Brazil's current Culture Minister, one can't help thinking that this performance involved a terrible paradox of sorts.