As a T-shirt at the Merriweather Post Pavilion last night put it, "The Grateful Dead are not the best at what they do -- they're the only ones who do it." No one else in rock 'n' roll even vaguely resembles the Dead's rolling, tumbling rhythms, slowly accumulating harmonies and gradually unwinding solos. Depending on the patience of the listener, the effect can either be hypnotically entrancing or numbingly boring.

The California sextet was not at its best last night as the tempos, solos and vocals tended to bog down from a lack of energy and direction. Nonetheless, the band roused itself often enough to cast its one-of-a-kind aural ambience and even produce a few galvanizing moments.

Those moments included the dramatic ballad "Looks Like Rain," powerfully sung by Bob Weir; the old eulogy "He's Gone," which built its harmonies slowly and elegantly; and the up-tempo "Sugar Magnolia," which pitted Weir's rock 'n' roll vocal and rhythm guitar against Jerry Garcia's psychedelic bluegrass picking. Low points included a sluggish cover of Steve Winwood's "Gimme Some Lovin' " and Garcia's mumbling vocal on the drowsy "Stella Blue." The Grateful Dead return to Merriweather tonight. -- Geoffrey Himes