I watched Lost back when it was on but quit around season 3 I think, it just wasn't going anywhere. Brilliant first season as well, but I gradually lost interest (as expected).
Well i was in the same situation. Started watching it when it was so popular, but gave it up after third season, there was too many strange/unclarified things.
But now when i knew it was over I started watching this again, this time with my brothers to finally finish the series. We're finishing seas3 now