I recently watched the original Oldboy by Chan-wook Park on Netflix. When it first came out for rent, I tried to watch it several times, only making it halfway through the film each time. It wasn't the plot or the violence that stopped me from completing the movie. It was simply I had no interest in finishing the film.
But having watch the whole movie recently I was blown away the the twist-and-turns. It's an intense vengeful movie. I am hoping the Spike Lee version doesn't pull any punches from the original, or go too far off the plot - just enough to make it standalone as a separate film.