Her ambition can be lauded or criticized, but the way in which that ambition informed her behavior during the LB, first with Rand then with Mat, is what compromised her as a character in my eyes. It seemed that she was ignoring both the will of the Pattern and common sense in antagonizing both, which is petty.  

Psychopath, certainly not. But if we look at just ToM and AMoL def split personality disorder.

I think it started when the coup ended and her reaction was to immediately yell at the Tower Aes Sedai for not standing up to Elaida and then turning around and yelling at the Rebel Aes Sedai for rebelling against the White Tower.  That was the point I started to hate Egwene (who I liked for the most part up until TGS)