Daily Kos gives this excellent tribute:
Kennedy was a liberal fighter in the old mold. The plethora of legislation he helped pass made life better for children, for the poor, for African-Americans, for immigrants, for workers. He didn't just give lip service to the rights of workers, he stood in their corner. He fought for access to health care and for quality education. And he opposed the likes of Robert Bork and others who wanted to trash the gains American women, workers and minorities had made over the years.
He will be sorely missed.
The Financial Times has a obituary here.
On BBC Breakfast their US correspondent suggested that Kennedy lost the 1980 Democratic nomination race against Carter due to the spectre of the Cappaquiddick accident. However, the more immediate cause was Ted Kennedy's disastrous interview with Roger Mudd of CBS, which Kennedy embarked upon without aides. Even the easy question "Why do you want to be president?" met with a response which was variously described as "unprepared", "rambling", "incoherent", "vague" and "repetitive". After that interview, it was down hill all the way as far as Kennedy's battle against Carter was concerned.
Indeed, Wikipedia observes:
Broadcaster and blogger Hugh Hewitt and Washington Post columnist Michael Gerson have used the term "Roger Mudd moment" to describe a self-inflicted disastrous encounter with the press by a presidential candidate.