In all my years as a DM I have only seen the spell reincarnation in action twice. The first time it was a sort of punishment (after all, how easy is it to be resurrected? Let's make sure you can come back as something stupid!) but the second time it was... much more.
The second use of reincarnation was much more thought out, and actually integrated with the setting design. Returning to life has always been a troubling question to me purely based on demographic problems. After all, if you can be brought back from the dead at any time, what's to stop powerful magnates from just reversing their own murders? Why doesn't every god ensure that their favorite kings and heroes live until a ripe old age and die of natural causes? For that matter, at that point why don't they just renew their aging bodies and make sure they live forever?
The solution I came up with for the 10th Age is probably not the solution that everyone else would stumble upon because it makes the game much harder and more restrictive for the players. The god of death, Akem, is a jealous god who guards the natural order fiercely. Those who die are simply not released from his realm. Resurrection magic is highly restricted since it must defy him and he has been known to go into open holy war in the past against faiths that break his restriction and snatch back the dead from his realm.
So what about reincarnation? Well, I had long ago decided that the spell had to be mediated by Akem to function at all; a sort of request is filed with the god and Akem chooses to respond in whatever way he likes. It is less odious to him, as it does not return a soul into dead flesh (you can imagine how much his priesthood love liches, vampires, and the like) so he is often more willing to do it.
However, it still requires a great effort on the part of another god to convince him to allow a mortal soul to return to the world. As his priests are fond of saying "The gates of Death are closed," meaning that once a spirit has passed the First Gate of Death (of which there are seven) there is no going back. "Cursed is he who troubles the dead," the scriptures run. Yet in the case of those who died nobly, fighting for their faith, there is some minor leeway. Indeed, perhaps even bodily resurrection could be achieved if the remaining characters went on a particularly difficult quest.
On Tuesday, Oloz Slave-taker was killed. He went down into the old converted Claustrite crypts beneath the Temple of Ashad to help clear them out of Ashad's servants so the temple could be claimed by the priests of Aros. He fell doing battle with one of Ashad's chief and most powerful creatures on the mortal plane: a bone weird, which was guarding his cult-statue.
For two reasons, I decided that this was worthy of a reincarnation. Though he was only level 4, he perished doing the work of Aros after a lifetime of evil works. He had converted to Arodian worship and thrown off the shackles of Ashad's madness. Additionally, he died putting to rest a necromantic horror, and Akem despises all abominations of Necromancy. For these two reasons, I allowed the reincarnation to go forward. Daelus Windspeaker, the high priest of the temple for which they worked, was given a dream by Aros granting him permission to continue.
Oloz has been given a chance not just at redemption, but at true rebirth; he was remade as a satyr, and his story continues rather than ending with his gruesome death. Ain't fantasy grand?