I'm really torn about Future's End. There's so much to like/admire...and yet, it just doesn't do if for me. Not quite sure why. As time travel/old Earth episodes go, it's better than Time's Arrow, but not as much stupid fun as Assignment:Earth, Little Green Men or Carbon Creek (I know that's technically not time-travel, but I don't even want to mention Stormfront).
The best thing about S3 was ditching the Kazon. And it gave us Season 4.