Decided to watch the season 4 dvd set in a marathon session yesterday and earlier this morning. (Found the dvd set at a church rummage sale awhile ago for $2, but haven't watched it previously. I don't have any of the other seasons on dvd, other than the pilot).
I never really watched Lost, other than watching the pilot episode previously.
Despite not knowing much about the details of the show, I found season 4 somewhat compelling to watch. There were several scenes which I suspect would require some knowledge of previous seasons for context, but overall I thought season 4 was watchable as a standalone.