I fucking loved Lost. Properly loved it. Would obsessively watch and rewatch episodes, took part in all the in-between seasons extra-curricular internet stuff. It was a major part of my life during the major events in my life so I will always have a very sentimental attachment to it which makes it hard to judge properly.
I will absolutely stand by the first few seasons as exceptional network narrative TV. I think it deserves an enormous amount of credit for changing the game to allow showrunners to decide their own end points. That said, I can fully understand why people jumped off board with it as it became apparent they had no idea where they were going with it. Despite that, I actually really like the way it ended with a bit of distance from it. Every character ended up with very full arcs that were emotionally very satisfying. The journey to get there would have justified the ending even if I still hated it though.
If I were to make a list of my favourite TV drama “moments” I think Lost would end up being very over-represented.