Wheatley is bad

Galdos is good

space

sentry bot orchestra

Chell in middle of farm

with companion cube

Yes, GlaDOS make people do tests that kills them. But we found out in Portal 2 that she was just doing what the researchers were already doing; there was nothing safe about the old test chambers built by humans. That's why they originally only use homeless people etc. People dying in droves was the norm. GlaDOS merely decided to do to the researchers what the researchers have been doing to others for all these years.

GlaDOS was not crazy at all; at least, she wasn't any more crazy than the Aperture staff members. When Cave Johnson went mad, he fired all the sane employees who object to lethal human experimentation. GlaDOS became what she was because of the company she was keeping. It was the humans who made her bad. And at the end of the 2nd game, she is still bad; it's just become pointless to punish her any further.

Too bad for Caroline, but GlaDOS has the right to not be schizophrenic. Caroline was never put into GlaDOS willingly anyway, and who knows if there was anything salvagible from her programing anyway. One thing that got GlaDOS angry was all the extra core programs put on her, telling her to do things. Chell got rid of them, which explained why GlaDOS was more stable.

Finally, there is a hint from dialogue that wild life and humanity have survived on the surface after hundreds of years, so Gordon Freeman must have won Earth's freedom from the Combine.

is not a good guy. She had a bad upbringing and had reasons to do what she did, but that doesn't make her good. And she still wasn't good at the end of the 2nd game.

that actually real ending

you will understand what i mean when you play it

assuming saving chell is good

the part of her that made the decision to do so, Caroline, is completely deleted at the end exactly because her action exposed her location in GLaDOS's files. So that "friend" part of her is no more regardless.

p.s. It is interesting that we find out Cave Johnson was the one responsible for forcing all Aperture employees to get involved in testing themselves. So nearly everything GLaDOS did as a villain was an imitation of what her former masters did, albert hers is more deadly than usual.