Infamous already for long-winded posts, I'll try to be brief: simply the most original and soulful ensemble to come out of its era. Combine three excellent vocalists in rowdy, loose harmony, driven by fretless bass and barrelhouse piano, planted in Levon's laid-back beat, and spiced up with Robbie's stinging guitar and Garth's rollicking, unpredictable organ fantasies. All with lyrics that evoke "the old, weird America" - as coined by Greil Marcus, who wrote one of the best books on The Band. Great writers are drawn by great writing, and so The Band has inspired many full-length books, including Robbie Robertson's memoir, a response to Levon Helm's memoir. The Band's universe is a deep and rich well.
Your next stop should be
http://theband.hiof.no, where full lyrics are posted along with interviews, essays,and etcetera.
The Band's songs never seem dated to me, unlike contemporaries such as Jefferson Airplane. And they're great fun to play and sing, so that's the best way to get into the music.