I think if I were to give the class a re-write, I would substantially modify their spell list to include more of the utility that a standard magic-user would have... perhaps, by adding spells that simply have facelifts to fit the 'style'.
For instance:
Charm Person - the pyromancer produces a small blue flame that dances about in a hypnotic way in front of the chosen target, leaving him or her very susceptible to the pyromancer's influence.... etc.
Floating Disc - a floating disk of black charcoal like material is summoned. The disc appears to smolder and burn around the circumference. At the end of the spell, the disc crumbles into ash.
Dimension Door - the pyromancer brings forth a column of fire that the caster steps into with a flash and is instantly transported to another location chosen..... etc.
And so forth for the rest of the spell list.
As a player, I have never had trouble playing themed mages. I try to create the visuals that support any particular chosen theme. I have played a Ice Mage before, a Fire Mage (like above), and more by simply changing minor details in spells to suit my character's theme. I even briefly played a flamboyantly homosexual magic-user where I colored all my spells with pink and rainbow themes. He even summoned (by Mount spell) a "my-little-pony-styled pink" horse to ride.... that character did not last very long though
