Yea life would be shitty after spending 20 years in prison for a crime you didn't commit, but I bet if we ask all the guys who have had that happen to them most of them would be happy that they weren't executed. Wrongful convictions are absolutely a valid argument against the death penalty, and for me personally it's the only reason that I'm against it. Look at that poor guy in Texas, who got executed for burning his house down with his kids inside. It's pretty much accepted now that he was wrongfully convicted. Don't you think he would rather be alive and free now rather than feeding the worms?
I definitely think some criminals need to be put down like the rabid dogs that they are, but cases like the one I mentioned and the whole deal with the FBI bullshitting about DNA evidence for over 20 years gives me pause.