While he has always been one of my favorites, I believe that Revenge of the Sith has sealed Obi-Wan Kenobi as one of the most complex characters to ever grace the screen of a Star Wars film. From the first time we saw him (howling and waving his arms around like a madman) he was different. Ben Kenobi was the first to introduce us to the Force, the first to utter the words "lightsaber" and "Jedi Knight." He gave us a history lesson, woefully incomplete, until now.
Obi-Wan's actions and motivations have been questioned for the last 28 years, by the fans as well as by characters that he interacted with in the original trilogy. Portrayed by the late Sir Alec Guinness with an elegance that became an integral part of the character, Obi-Wan was noble in any surroundings. We knew immediately after his revelation to Luke that something dreadful must have happened in his past. We watched in admiration as he walked into that "wretched hive of scum and villany" as if he owned the place. And we watched, shocked, as his cloak wafted to the ground at the hands of the despicable villian.
It was during his spectral appearances in the subsequent films that he truly began to reveal himself. His sacrifice had initially seemed to simply be a distraction to allow his allies to escape, but now we began to suspect more. His exchange with Yoda (as that sly old Master revealed himself) was witty and touching. His plea for Luke to finish the training was desparate. His insistance that our reality is dependant on our "point of view" was almost disturbing.
Fast forward twenty-five years and we finally get to meet the young Obi-Wan. As a Padawan, he was both defiant and strangely orthodox. As a young Knight training his own Padawan, he seemed to forget his own impetuousness. And finally, as a Master pitted against his best friend, we begin to feel the weight of the twin Tatooine suns.
Obi-Wan's self-imposed exile was a terrible burden. For nearly twenty years, his most frequent visitor was the ghost of his slain mentor. He was alone with his perceived failure and the memory of a friend turned enemy burning on the sand.
Revenge of the Sith added an element of tragedy to Obi-Wan's character. This makes Sir Alec Guinness's performance in the original films that much more compelling. The sorrow was always there, we just never knew why.