Great watch, would watch again, and can recommend.
While the setup is a little bleh, it serves a point, but I could literal start the movie at Samuel L. Jackson's office and be fine.
Once in 1408, the intensity creeps perfectly. It really gives you the atmosphere of a cat playing with its food.
It'll mess your head a little, but that's just from a great John Cusack delivery and wonderful cinematic display.
And the ending is almost perfect: the are two minors points that could be bad, but they're unclear.
As the manager said, "It's and evil room.