He cuts his own arm off alright. That’s pretty much what 127 Hours boils down to, despite being directed by the eclectically talented Danny Boyle (Slumdog Millionaire, 28 Days Later). This dramatization of the real-life ordeal of Aron Ralston, who in 2003 found himself pinned by a boulder in a remote Utah canyon and had to perform self-amputation to escape, is a riveting, excruciating account of that experience. But those of us who were hoping Boyle might turn this into something extraordinary — perhaps along the lines of Gus Van Sant’s existential Gerry, featuring another back-country trek — will be disappointed. With James Franco as Ralston.