Kevin Spacey'so performance

As much as I adore KS, and particularly American Beauty and The Usual Suspects, I fail to see any particular nuance to his performance. I knew from the beginning that we were being "punked," which may be more the fault of the director, but which was made more excruciating because of Spacey's habitual deadpan acting. I do not tend to enjoy stars in lead roles, but withstanding such, I wonder who would have given a less leaden, more nuanced performance? Any opinions? I'm not saying that Spacey was bad, just annoyingly predictable, similar to Winslet. The actor whim I felt most nailed a fabulous ambiguity was the attorney. Never knew what was behind those bad teeth and Texan accent, unless the ponytail was a give away for "liberal," no-death penalty vibe.