I have been lucky enough to have heard him speak 4 times - twice at Faneuil Hall in 2006 where he was incredible and got endless standing 0ovations - and deserved them. The first time was Kerry speaking to a smallish (500) crowd in NJ trying to get people to volunteer (or at least vote for Corzine). Even in the wake of having lost the year before, he was charming, charismatic and as good as anyone I have ever seen in speaking one to one with the people there.
The part of the speech that this reviewer liked best was actually derived from a speech he gave at Fanueil Hall (one of the two I saw) that was on the right and responsibility to dissent - which he gave on the 35th anniversary of his speaking before the SFRC. (If you question his ability to speak, watch this http://www.c-spanvideo.org/program/WarinIraq7