Re: What exactly is Regeneration like to the Doctor?
I felt that the Ninth Doctor's explanation was geared more to reassure/placate Rose. The Doctor lies, we know that for certain. He obviously wasn't the same man with a new face. Same memories, yes. But a very different personality and temperament. He was being unusually frank with Wilf. Just my take on it, and I may be over-rationalising a tad.
Life is full of disappointments. For instance, I really hoped "Chariots of Fire" would be a remake of "Ben Hur" with flame throwers.