Guster isn't the most prolific group; the forthcoming Easy Wonderful is its first album in four years. However, any new release from the Boston band is worth the wait, and Wonderful is no exception. A far cry from the stripped-back bongo-folk of Guster's early albums — and a far more upbeat collection than 2006's Ganging Up on the Sun — the album bursts with shiny-penny harmonies, feel-good tempos and expansive instrumentation. (Ukulele, horns and strings bounce in and out of the mix.) Later-period Talking Heads and the Beatles remain touchstones — but now more than ever, it's obvious that the members of Guster are growing up along with their audience. Opener Everest has warmed up audiences before Wilco, Neil Young and Minus the Bear (including at the Firebird in July). Amazingly enough, the band's snarled rock hurricanes — a bit twangy, a bit country, a bit dirty and always full of sincerity — have held their own.