I think he was quite dynamic, but in the wrong sense. He went to bloodthirsty killer, murder of his Clan. To loving older brother, trying to save the World.
In that mix somewhere Kishimoto failed him big time. For me it's not the surprise factor, like, 'Oh, he's a good guy now' -- It's on the line of how it was portrayed between those two characterizations.
I find Itachi to be too overplayed on his character. What depth he has isn't really that deep, and the only interesting thing about him was his fighting style. Which was quite simple and overplayed by Kishimoto, basically wank wank wank.
I do praise Itachi on his character quotes though. He does by far drop the most interesting phrases that make you think.