Jimmy Steele is angry... and not much else.  A lot of his less-than-cheery demeanor seems like it could be traced back to his "tough" childhood.  I'd say that this left him with a lot of pent-up aggression, except he doesn't keep it very pent-up.  He often acts rashly, exploding in "tantrums" when things don't go his way.  In fact, more than once the USXWF management has had to intervene in Jimmy's desires.

His anger also provides him a source of strength to compliment his stiff training schedule.  It also leaves him in a very sadistic state... a "bloodlust" that becomes sated only by inflicting as much pain on his opponent as possible, often dragging out the pummeling 'til long after a match ends.