Just wanted to say I thought this Special was excellently done and Michael Emerson (Ben Lynus) narrating was perfect!
It pretty much tells you everything you need to know about lost! Although you'd miss a lot of details and drama and the overall experience i think you could pick up the plot of Season 6 from this. Id recommend this to newcomers definitely if you don't have the time or cash to buy/rent the previous seasons!
This was also fun to watch as a veteran viewer of Lost. The explanations were done well and Michael Emerson delivers it in the right way!