His acting in the scene in his little hut of a house on Tatooine, is without question the best acting in the entire SW saga. With the most subtle expressions, he conveys emotions far deeper than all the screaming in the PT. The scene turned out to be so powerful (thanks to Guiness' powerfully understated acting), that Lucas should have seized upon it and built the entire saga around what Obi-Wan said in that hut, instead of spending the next 5 movies trying to explain it away. Guiness single-handedly turned SW from a fun flick into a real movie, and not only the best of the trilogy, but among the best of all time.