I just finished the first two seasons of lost. Gets a 8.5/10 from me.
Didn't give it a 9 or 10 due to some continuity issues. Don't get me wrong though its an awesome show.
But it seems at times the writers paint themselves into a corner, and then next episode bam a boat in the middle of the water. Or the fact that somehow Michael and Sawyer got back to the island after being miles out without it ever getting dark.