The fact is that Obi Wan is an intelligent Jedi. He is inferior to other jedi in many ways but he is the best thinker of them all.
Obi Wan likes to do things with thought, like when Anakin wanted to destroy the droids after they infiltrated a base. Instead, Obi Wan pulled out some bomb pellets from his bag and told him there are easier ways of dealing with them. Anakin said, "ah no fun"
Also in episode 3, Obi Wan was patient in the Elevator, thinking his way out of the situation where Anikan again was impulsive and cut his way out of the elevator. Obi Wan just contacted R2 and allowed for him to move the elevator meanwhile Anakin was agian impulsive.
Again in Episode 2, instead of running crazy looking for the assassin in the bar on Coresant he went for a drink and allowed anakin to run around insane looking for the Assassin. Patiance paid off as he caught the assassin.
Even in Episode 1, he killed Darth Maul because Maul didnt expect that a padiwan could pull off a stunt as he did. He underestimated him!
This is Obi Wan, a thinker and patient Jedi, always looking at the bigger picture. Even when he faced Darth Vader he told him not to jump from the lower ground. Sure enough he did and it cost him his skin, arm and legs.
Obi Wan is no slouch, and when he saw four arms waving at him he decided that he narrow it down to three arms! Then Two!
Seeing this Grievious took off running. Mind you that Grievious put up a hell of a fight even with his chest crushed and all but Master Windu, he still managed to smack Obi Wan around a bit. But still when Obi Wan found his weakness he exploited it.
Obi Wan was the BEST strategist with a light saber....
Obi Wans last act was allowing for Darth Vader to strike him down so that he man commune with the Force and guide Anakins son from the dead. His last words, "If you strike me down I will become more powerful then you will ever know."
Again Obi Wan thinks out of the box as did Qui Gon Jin! Its why Qui Gon Jin was able to be the first jedi to commune from the dead with the living.
Obi Wan took away Grievious arms and took away his advantage. Leaving him with only one option... RUN!
I think his resume speaks for itself
Obi Wan is a legend of a Jedi...