CLASSICAL MUSIC: San Francisco Symphony / Tilson Thomas; Barbican Centre, London

Sunday evening's Barbican "Great Performers" concert by the San Francisco Symphony under Michael Tilson Thomas opened to the commanding strains of Aaron Copland in "monumental" mode. Symphonic Ode is an early work that combines premonitions of Appalachian Spring and Lincoln Portrait with hints of jazz. It was given a bold, confident performance, a little lacking in weight and not without the odd imprecision, but cumulatively impressive.

Tilson Thomas's account of Debussy's La Mer paraded a mass of distinguished instrumental solos but was otherwise oddly mannered. The very opening was pensive and rushed, even a little nervous, although the horns rang resplendent just before the final peroration. The second movement was better, its later sections a dancing, elegantly voiced representation of the "waves at play". Then, towards the end of a fairly unsubtle "Dialogue between the wind and the sea", Tilson Thomas summoned optional trumpet parts but spoilt the effect with some tiresome rhetorical pauses. One had the impression of a compelling performance in embryo - sketchy, experimental and likely to change direction at the next opportunity.

The concert's second half sprang into action with the exotically coloured Parade that Lou Harrison wrote for the opening of the orchestra's 1995 season, a sort of "Scherzo a la San Francisco", brilliantly scored, rhythmically pungent and immediately memorable. The lion's share of the programme, however, was given over to a well-planned sequence of scenes from Prokofiev's Romeo and Juliet, opening with the ballet's "Introduction" and closing not with the expected "Juliet's Death" (which wasn't actually played), but with the fast and furious "The Death of Tybalt".

Again, there was a maddening combination of the stylish, the sensual, the slick and the eccentric. The "Introduction" itself was beautifully shaped, and inspired a glamorous flood of violin tone; "The Street Awakens" featured perky bassoons, and the "Balcony Scene" exquisite solo strings and remarkably fine brass. But there was the odd disappointment, too. "The Duke's Command" (which, in Prokofiev's second orchestral Suite, announces "Montagues and Capulets") saw a lack of dynamic contrast. In fact, quiet string-playing was generally conspicuous by its absence, perhaps because the orchestra was adapting to an unfamiliar acoustical environment. "Mercutio" and "The Death of Tybalt" were incisive but uninvolving; it was almost as if over-familiarity with the music had caused the orchestra to lose interest in the drama.

Throughout the sequence, Tilson Thomas employed the odd affected ritardando - and never to more exasperating effect than at the very end of "Tybalt's Death", where the broadening swung into blatant interpretative overkill. Too much bravado, I'd say, and too little of the sensitive musicianship that characterised the best of Tilson Thomas's days with the LSO.

Perhaps the idea is to provide interesting points of comparison with the more thoughtful, structurally integrated approach to interpretation for which Herbert Blomstedt - Tilson Thomas's immediate predecessor at San Francisco - was famous. My ideal would be a workable balance between Blomstedt's sense of proportion and Tilson Thomas's natural charisma. Play to the gallery long enough, and everyone starts to get bored.

Robert Cowan