I’ve gotten most of my friends to read Umineko, including @smileypers0n. Now, that said, I also regularly shilled it when I was the president of my school’s anime club, and for every person I got into it, there’s probably a couple dozen who never thought about it again after Club. (Still, I know I introduced it to at least six people who I know are know full-fledged fans now, three of them having cosplayed characters.)
I also got my stepmother to read the manga, which she seemed to enjoy- except she stopped at Episode 3. I think the volumes just got too big for her to consider reading. This isn’t the only time the manga has scared someone away- I have a friend who I got to read all of the Higurashi and the Rose Guns Days manga, but who’s borrowed the first volume of the Umineko manga for almost three months, and hadn’t read a bit of it. (Even though it’s honestly such a quick read.)