half way through watching it i thought for sure he had to be a intp. the voluntary isolation, the restaurant scene, his 'depravity' yet apparent lack of sex life, his obsession with adler..
however, someone was saying earlier that there's no way an intp would be leaping around, brawling with people, but i can tell u, i'm living proof that an intp can most definately engage in fights and other 'adventurous' activities like leaping around a city.. mostly getting into fights.. he doesnt do this because he's a go go action guy, he does it because it interests him. the thought of beating another man to a pulp in the most efficient way possible excites him. the actual beating itself just doesnt do much for him, other than validate his deduction.
i might add that in a real confrontational situation, plotting out your every strike in your head before hand, reeaally doesn't work... but it was cool in the movie.
as for the moments of extraversion, its entirely possible for an introvert, even an extreme intovert, to appear, even feel ultra confident, in front of groups of people. me, for example - when i'm drunk or arguing about something i believe in. from what i gather, Holmes was into his cocaine (which has a somewhat lifting effect) and he was always knew he was right.
there i've done it - related an awesome fictional character to myself in an almost coherant way. you could say it was.. elementary, my dear personality type forum...