From: Liverpool, England
I first became a Beatlemaniac: in the summer of 1989; I went to France with a high school tour group, and some of the kids in the group were Beatles fans and piqued my interest. I wound up spending all my travelers' checks on Beatles CDs after I got back.
Sound: Well, they sound like the most popular musical act of the 20th century, and like they deserve it. Especially remarkable are that they started as a fad yet remained popular for more than a year or two; that they had coattails, as others followed them to the new heights of songwriting quality they had achieved; and that they used their massive popularity to expose the world to experimental music the likes of which only a tiny fraction of their audience would have ever gone near otherwise.
Though I tended to prefer the late, experimental stuff during my Beatles-listening heyday, after I started playing music and writing songs myself I became much more appreciative of the moptop-era stuff.
Further listening: Criminy, how am I supposed to pick highlights of the Beatles' discography? It's all highlights! Well, in addition to the songs that are already in my top 100, here's a pretty arbitrary sampling of all-time greats: