By DCist contributor Sarah Sherman

There has been plenty of contentious debate about Mumford and Sons, whose popular debut Sigh No More landed in 2009. Fans laud their radio-friendly folk rock, praising the band’s beautiful vocal harmonies and emotional acoustic crescendos. Critics argue that the group is just an amalgamation of folks like Fleet Foxes, Noah and the Whale, the Avett Brothers and Kings of Leon, slapped together for shallow efforts at an honest, family band feel.

Thursday night’s raucous, sold-out show at the 9:30 Club was so much fun that I had trouble caring about the naysayers. Mumford and his fellows are charmers, and they spread their feverish energy to every corner of the club.

The voices of the four men rang out in perfect harmony as the band opened with “Sigh No More,” with only a quietly strummed guitar underneath. But the powder keg sparked as Marcus Mumford tapped the bass drum at his feet and Country Winston joined in on dobro. The song is a typical example of the Mumford and Sons sound — almost mournful moments chased by rumbling bass, clattering pianos and swelling guitars. The formula made for a night of mood swings, from forlorn love songs to bluegrass jams to rock ‘n’ roll madness. But the undercurrent of ferocity kept the packed house riveted, and favorites like “Dustbowl Dance” and “Little Lion Man” quickly became full-blown singalongs.