Not bad but expected more from the plot

Rating: 7/10 (16 March 2010)

The plot was obvious but could be salvaged up till DiCaprio runs up the lighthouse finding empty rooms after empty rooms. Is he sane or not? That's about to be irreversibly unraveled. If instead this is kept to the very end where both answers were plausible, this would have been a great plot.
Maybe with DiCaprio staring out from a cell's window in the final scene, thinking out loud: How can I get out of here?
Now that might drive everyone insane. But they might come back again and again to seek sanity...
As I walked out commenting to my friend, Scorsese did 90% of the job, I was impressed by the directing and acting. Now I give it an 7 because ultimately, I much prefer keeping the conspiracy proposition alive. Maybe Scorsese was bound by the rights to the novel. But what a pity, the plot could be as good as "The Departed".