I've watched it since the first episode but that doesn't mean I've been able to make sense of it in total as the writers have seemingly deliberately made it obscure, meandering, contradictory and plain hard to follow.
Several times after yet another trek through the jungle I've been on the verge of giving up, but feel that I've invested so much time that I must see how it ends. The final season has been very poor imo, raising more and more unanswerable questions and taking us deeper into the rabbit hole than ever.
I'll reserve judgement but would just add that it's cardinal sin is running way too long. It should have been tied up after four seasons.
Six Feet Under is how to end a series but that's a vain hope for Lost.