??? Power wise:
- Oda stated and showed multiple times that an Admiral can't fight properly without lots of collateral damage
- First thing Kizaru did when he got to Egghead was go over 3 things that couldn't be destroyed under any circumstance
- Kizaru wasn't trying to fight Luffy(blatantly said that he doesn't have time to fight as his target was getting away) and slipped away numerous times
- Kizaru kept wavering was caught by surprise numerous times
Character wise:
- His motto is unclear/uncertain justice and he fit the bill perfectly.
- Emphasized numerous times that he didn't want to do the mission, was seen hesitating, closed his eyes when attacking a friend, and stayed down because he completed his mission and was morning his dead friend
- Was laying down after WSG but got up immediately when Bonney and Sento were ordered to be executed, and didn't make another move until ordered by Saturn
Kizaru wasn't a disappointment at all. It's just people who were expecting some final villian bout in a transitional arc.