A while ago I watched and reviewed Shutter Island. I thought it was an okay movie with a twist that was partially ruined by reviews I’d listened to beforehand. I’m watching it again this morning (legitimately through Netflix) and I have to say it is really worth a second viewing. Knowing the twist gives you a whole other appreciation for characters’ actions and expressions throughout the film.
If you’ve seen it and were unimpressed, I’d say see it again.
If you haven’t seen it, I’d say watch it a couple times.