I remember the last season of Lost having a couple great episodes, like the origin ep for Richard, that made me think the season would deliver. But ultimately the finale felt empty despite a couple great character moments, and the ending was stupid. The biggest offense was how they ruined the best character on the show, Locke.
S1, S2, half of S3, and S4 are still great in my book. I like shit that has multiple characters I really enjoy and Lost really did a great job at it. Locke, Sawyer, Sayid etc. And I get weird nostalgia feels whenever I see an episode or hear the music. But yea...the show shat the bed in the end.