Just because it wasn't your thing doesn't mean it wasn't significant. I can't stand Elvis but I'm not dumb enough to say he wasn't incredibly important in the history of music.
I don't think Nevermind was Nirvana's best album and I don't think Nirvana were the best grunge band but Nevermind was the album that really started the explosion of grunge in the early 90's. If it wasn't for that record I think grunge would have remained an underground genre and just another branch of punk