im an assassin who has the ritual stone instead of the thief stone, heres why:

1.its fun as hell
2.say your hidden in a dining hall, see an oppurtunity to kill one of hte vampires around there, you one shot him... cuz ur in stealth u know how it goes... anywayz, you get seen by a different, strong vampire that is harder for you to down without being in stealth, so wut do u do? use the ritual stone, ressurecting all nearby corpses, that means the vampire you just killed and possibly others will attack all of your enemies, making a small army... which is fun as hell...

I never even knew about this Stone! Is it duration or until they get killed? I just read it works on all enemies, even Giants and Mammoths!?

I like the lovers stone.
Raises all skills faster.

nvr tried it on giants and mammoths, i should though... and its a duration thing, not mass dead thrall D:sadly...

plz... lvling too fast as is, prefer to just laaaaaaaaaaay back.... and stab ppl until im max lvl... gotta make skyrim last, ya know?

Good point, i only use the stone when i get stuck with a certain character.
Otherwise then that i just prefer to stay with the warrior stone or the serpent stone (lets you shoot toxic, that is pretty cool )

nvr heard of that stone ill have to check it out (serpent stone that is)

Well, the serpent stone lets you paralize somebody for quite some seconds.
A life safer that one.

There are no exceptions mentioned ("creatures and humanoids"), so I would say so. (doesn't work on Dragons, like every other reanimation spell)

It's nice but like some of the others it's only a once per day use. Way too limited for my tastes. I prefer the Lord Stone. Hard to beat full time resistance to physical and spell damage.

I love the Ritual Stone. You know how the end of the civil war quest, where all the soldiers are listening to the leader give their speech? Use the shout that summons a thunderstorm (will kill everyone in that area), drag everyone close together, and use the stone power. Over 20 temporary undead minions (and, if I recall, undead minions do not turn to dust by the power so you can just cast it again the next day).

i use 24hr w8 each time i use it

UESP says it isn't duration based.