I enjoyed season one of LOST. Season 2 wasn't nearly as quality. Season 3 gets going again after a bit.
So far I have watched the first 12 episodes and my feelings are mixed. At first it annoyed me with some of the cliched US tv characters, but after a while certain characters stand out more than others (I like Charlie, Locke and Sawyer).
I love the intrigue on the island, but I do think the back stories/flashbacks tend to drag on longer than necessary (I think some of the footage has been added into the DVD release).
I'm hoping there is more of the present day stuff and less of the past as the series progresses!
