Like any prequel character other than Palpatine, his personality was completely bland with little notable character traits to be discerned beyond just being Samuel L. Motherfucking Jackson with a Purple Lightsaber. His entire role in Revenge of the Sith was also absolutely stupid, considering not only was he just repeating the "I sense a plot to destroy the Jedi" line from the previous movie and doing nothing about it, but when he actually confronts Palpatine he does so in the stupidest of manners. He just barges into his office, a secluded place without any non-combatant witnesses, an act that could easily allow Palpatine to twist the events in a favourable light for him, as he does (something that's even expanded on in the novels). Also, whilst his act of trying to kill an unarmed Palpatine was a necessary one, it also shows how much of a hypocritical Jedi he was when Anakin of all people was reminding him that it wasn't the Jedi way.
2/10. Legends and other Expanded Material would bump him up to about a 4-5/10.
