I never met Kennedy although I saw him from afar once at a rally. But Nomi told me a story once about how responsive Kennedy was to his constituents. If I recall the story correctly, Nomi's mother was working with a group fighting to get the Americans with Disabilities Act passed, and Kennedy spent an hour with them in his office, listening to their concerns.
It is hard to believe he is gone. Someone will succeed him, but no one can replace him.