i think Aizen lost something close to him because of the way things are in Soul Society and the imperfection he's experienced in his own life. i think his intentions aren't necessarily evil, their just up front and personal.
Aizen is obviously on the same level of power as Unohana, Shunsui, Ukitake and maybe Yama-ji. but, i think it's more than just power with Aizen, it's deeper and could be similar to what Ichigo is going through with his own power.
also, think there's a connection between Ichigo and Aizen, but it's yet to be revealed.