Not like I know the guy, but Johnny Depp doesn't seem to have been the same person after spending so much time with HST as well.
I think thats a pretty accurate observation. He seemed to have an affect on people he spent a substantial amount of time around. John Cusack was another.
It's almost like a benevolent pseudo-mystic-nihilism... I don't know what else I could call it. There was definitely a change, though.
For the record, HST hated the film.
I highly recommend the film "Where the Buffalo Roam" with Bill Murray and Peter Boyle. It' split into thirds with a frame of HST writing in his cabin. The campaign trail is cut to a short for one third of the film.
Murray filmed it right around the time of, or before, Caddyshack. It kind of frames his character in the latter for me. He was spending a LOT of time with HST.