We all have an opinion of this, but the fact is 60% of the world population lives in a country in which people are sometimes executed for their crimes, most important countries being China, The USA (most of states) and Indonesia.
I think this is a more advanced and modern world than it was decades or centuries ago, and I wonder why more than half of the world still applies death sentence. Sure, nobody likes rapists or murderers; neither do I. Killing them of course prevents them from commiting crimes again but that's not the solution,that's not why we created Penal Law; we created it to (basically) send people to jail so they learn the lesson. Some also say they never learn so it's better for everyone if we kill them...well that's what life imprisonment is for.
Now let's analyze some pros and cons of death penalty:
Prevents the person executed from commiting more crimes.
If anything, makes the victim's family, friends etc feel better as the murderer was killed (Retribution).
-We become murderers and violate the right to live.
-We can't go back or lift the punishment if we find out the criminal was actually innocent.
-There's no way the recluse will become a good citizen in the future (which is the main goal of Penal Law)
Death Penalty is basically an eye for an eye. And remember: An eye for an eye and we all go blind.