Robin Hanson gives the likelihood of cryonics working a 1%-3% chance. However, argues that the payoff from having it work is so high that such a low chance should still yield participation and advocation of cryonics. He thinks it is curious that we do not see a great deal of interest in it, and wonders what that can tell us about the human relationship to death. I think I personally would only want to do it if I knew I would be frozen immediately after, if not right before death, because otherwise the chances of coming back (i think) are too low to bother. With pets at least we could get away with freezing them right before death because we don't face the same restrictions in terms of having a death certificate, etc. However, I am not sure veterinarians would easily cooperate on this. It is something I have been meaning to look into more.