I was a rabid fan from the start, but then they did that season of alternating repeats (3rd season maybe?) that drove me right up the wall. 3 new, 2 old, 1 clip show, 1 new, skip a week altogether, 2 new back-to-back (so everyone's recorder misses the second one), 3 old, etc, for a whole freaking season.
Then the uproar over those repeats made them decide to just break the season over Dec/Jan the following season and not run repeats. They teased the replacement for weeks, telling us to watch the replacement for "Lost updates and clues!!" during the commercial breaks of the replacement show (and WTF was it called anyway?). Needless to say, the replacement tanked and was pulled after a couple weeks, who knows WHAT happened to the "new clues" we were supposed to see. By the time Lost started up again in the spring I couldn't care less.
I do miss it, though. I keep telling myself I'll rent a box set and run through a couple seasons some snowy weekend.