I don't know for sure how to think of this matter.
Apostles sure did something very evil but that doesn't mean they're doing evil all the time...
We've seen many apostles indulge in evil in even the most disturbing ways while we also have apostles that seem like they just accepted the evil they inherited after their sacrifice and remain quite passive like Irvine who isolates himself (though we don't know what he does on other times... Or what he hunts).
Other apostles still have lots of control over themselves which is a noticeably feature (since most of them are diluted uncontrollable psychos) due to their nature as the person they always were.
Grunbeld, Locus and even Zodd also belong in this category. They're not much different from normal humans... You might say the only difference is the power that was granted to them and the license to do whatever the fuck they wanted to do.
Turn into a monster and wreak havoc? No problem.
Turn into a monster and act human? Sure why not. It both works for them.
Be a human? That's a hard one. (Maybe the count got dragged into the maelstrom since he did something rather humane. Who says that the progress isn't reversable?)
So yes. Apostles are evil but some of them have intentions that could differ from being evil.
It also doesn't mean they aren't capable of doing good sometimes.
As for Rosine... We got to see why she turned out being evil, we got to see what chaos she caused, how she used humans as mere puppets and how she manipulated children. She was evil but I think she also had some good left in her when it came to Jill.

The complete nature of the apostle still has some mystery to it.
We've seen apostles helping humans because Griffith ordered them to do so...
But we've seen apostles helping humans by their own choice like the Count and Rosine (whether it was for themselves or not).