I was really disappointed in III probably it has to do with the fact that i watched the 3 movies in a row and i can't help but compare the last one with the previous two.

reasons for me not liking III (too many, but i'm only going to mention the ones i can think of right now):

-Vincent and the group of punks are very obnoxiously annoying
-no Tom Hagen
-not convincing: I don't believe Mike will let Kay have the children, I don't believe Mike won't remarry, I don't believe Mike will let Vincent be Don...
-Sophia Coppola...
-"I luv u, cuz..."