A WARNING FOR THE VIEWER: Purchasing the brand new, seven disk, 17+ hour DVD set of the second season of Lost may result in abnormally long sessions of television watching, with possible side-effects of eye damage, weight gain/loss (depending on how focused you are), deterioration of relationships, and muscle atrophy.
That's the warning label that should come with Lost: The Complete Second Season--The Extended Experience. Once you start watching episodes it's VERY difficult to stop. But if you were really considering buying it, you already know this: you've watched season one and are familiar with the show. If you've never seen it, then I suggest buying the season one set in addition to season two, and spending about two solid days watching every episode so you're up to date for the upcoming season three premiere. Even if you've been watching religiously like most fans, hitting up the season two DVDs to brush up on anything you forgot doesn't hurt either (you know the writers love foreshadowing and making every detail count).