Does using this spell actually affect other characters in any way? Because it doesn't really seem like a nice thing to do. The briefly summoned spirits don't seem to like it...
Good and Evil are all about perspective more than anything these. It is more the intention behind the use such as summoning the spirit of a murdered person to find out their killer, or realising the guy was a dick so you summon him so that he can never feel peace.
One thing that should be kept in mind, though, is that whenever a spirit is conjured, it means pain for it. There are situations when this can be done for the greater good, but generally a bloodthirsty sadist has more occasions and more use of the spell than a goody-two-shows. In case you are asking if there are souls that give something more of a response than the typical "Where am I?"/"Oh, the pain!" one-liners, indeed there are.
I figured as much, and I don't want to miss them. I just want to know if when I actually reach them, I'm not limited to being the mentioned 'bloodthirsty sadist' in dialogue options. That's not the kind of character I want to play. That's what I'm saying. That's how I look at it, but it may not be the way the game looks at it. As far as I see it, I'm not putting someone in a situation where they can never feel peace again, just putting them through a little ordeal for the greater good. I want to know if the game takes this into consideration or if it's going to automatically turn me into a prick. It's not just a matter of "Will I lose reputation for this?", it's a matter of roleplaying as well. Even if no one finds out, it's still not something I'd have my character do.
It doesn't affect anything in-game, except the information you sometimes get. Nothing alignment or reputation.
There are a few situations where rather than "You will suffer for as long as I want you to, now talk!" it's more like "I understand your pain. I only want you to answer a few questions for me and I will let you go". Not overly much (most of the evil examples consist of killing plot-crucial NPCs and forcing them to talk, and there are quite some occasions for that), but still something to make the spell useful for good characters as well.