The physician who tended Gage’s wounds, Dr. John Harlow, recounted the story... Gage, after the accident was “fitful, irreverent, indulging at times in the grossest profanity, (which was not previously his custom)... Gage was no longer Gage.’’
There's an article about him in the Boston Globe which you can read here.
That article includes a previously-undiscovered photo of the man, holding the iron bar which shot through his head.
Before you click on that link you might think you are going to see an horrendous mess. But no - Phineas Gage is scarred but tough and good looking. After the accident he lived in Chile and drove a stage coach - so it sounds to me like he managed pretty well, and wasn't the mess he is often portrayed to be in popular accounts. He eventually died of seizures, 12 years after the brain injury.
Still conscious, with a 3-foot-long 13-pound iron bar through his face, Gage said to the doctor 'Here is business enough for you.'
This makes me think that he had qualities, humour intelligence and toughness, which helped him to survive. The impression I get from his face - am I reading too much into a photo - the impression I get is of calm will. And while I would agree that the complexity of personality and memory is tied in with the inert matter of your brain, I also think there is this burning point of Will, infinitely narrow in time, which forms the structure of the brain by forcing connections, and can reform it after an accident or stroke.