There is little reason to embrace evil. We watch it's effect, we watch the consequences and we see that being good is not always rewarding, and weasels get free play.
This seems to show it all in a nutshell, annd there are plenty of sides to it al. There is the side of Drusilla where we see just why she is deemed dangerous. We see how demons have a few weak sides and all this is overcasted with the view of the growth of Angelus.
The views on old-times is done pretty well, it leaves us with questions, but also with another view on Angelus/Angel.
As we see how it goes back and forth and the view on the visionary Angelus, we also see that he is in a league of his own.