At the beginning of the movie, he was rather vain, and did not really seem to care about a lot of others besides himself. He was still kind enough to let Sophie clean the castle, and even tried to break the curse on her. Not to mention he had taken in Markl as both his ward and apprentice. As time goes on, he becomes more gentle and caring for everyone, Sophie included.
Howl is renowned for his stunningly handsome features, and a gaudy sense of style. At the beginning of the film, Howl had blonde hair, but because of an incident while Sophie was cleaning Howl's bathroom, Howl briefly had orange hair, before it turned black. In the book, Howl had naturally black hair.
Howl Jenkins Pendragon was born in 1873 supposedly in England, but resides in the hills of the imaginary country Ingary.
In the book sequel, he and Sophie are married, and have a son named Morgan.