In my humble opinion, probably the best TV show ever made, and if not that, by far the most ambitious.
It is original, inspired, emotional, sometimes cheesy, sometimes funny, sometimes annoying, always keeps you guessing, has some of the most amazing cast of characters you'll ever see and it all makes you feel like you are witnessing something truly "big", with gargantuan ramifications, and the best thing is that it actually delivers.
Contrary to what seems to be the general opinion, i consider the Lost finale (the entire last season actually) to be "the" most mind blowing, poignant and satisfying finale in any long running TV series.
At the time, the level of anticipation and speculation was unprecedented (even George Lucas admited, prior to the finale, that he wouldn't miss it no matter what) and it still managed to fool everyone, to bring the entire story full circle, in the most creative and memorable way possible, though even today there are those that don't "get" it, and keep a certain, completely wrong assesement of the finale, alive (i won't say more, as it is the biggest spoiler of the show, but i'll just add that reportedly, R.R Martin caused Damon Lindelof, the creator of the show, a mental breakdown when the later found out that, a writer of such caliber got the ending competely wrong
There's also this myth that so many mysteries/questions were left unanswered, which is completely false and there have been countless amazing articles along the years, explaining the subtleties of the show and how it connects (almost) everything.
Fake edit: i came here to quickly say "watch it", and found myself on a trip down the memory lane, so thanks for that OP
Oh, and WATCH IT!