Other than thinking that his nobodies death scene(and Vexen's)were absolutely horrifying in Re:Com I never gave much thought to him. As a human though I've grown to really like and respect him. If they were going for atonement I thought his was one of the better done ones. I also like how they showed his curiosity and sweet nature in his facial expressions and way of speaking. He's adorable.
After finishing the game I went back and looked at all his scenes as Zexion from Re:Com and KH2 Final Mix, and the difference a heart makes is striking. He had an evil, mysterious, manipulative, and stuckup-ish air about him as Zexion,but as Ienzo the curiosity is still there but it's sweet natured instead of malevolent. Even his voice inflection and tone is different from his nobody. He just doesn't give off Zexion's darker air anymore or tendency to commit murder lol.
I like his scenes with
Sora, Demyx, Ansem The Wise(although the execution could have been done better here), and the last scene when he was smiling sweetly down at Namine when she woke up. He looked so happy and proud that he could do that for her. Although I'm surprised Namine didn't run out screaming considering who she wakes up to lol.
In future titles he can take over the 'here's what you need to know about this nonsense plot' role from Ansem the Wise and the Disney wizard.