Well, really, I'm on the fence.
After all, the death penalty is an extreme solution, but most of the time, follows a principle that has been around for a long time. Sure, it gives them the "easy way out" but if you follow the "eye for an eye" rule set in ancient times, it is a very logical punishment for murder.
Plus, a really good argument would be this: Prisons are getting overcrowded. Everywhere. USually for pitiful reasons. While taking out mose of the petty reasons would dramatically decrease the occupancy, you have to realize that the security is not infallible. Never was, and porbably won't be for a long time. There is always the possibility that someone will escape. Always has been. But the overcrowding makes it all the more risky. One murder, maybe, you can survive. But if you consciously kill another on purpose again, the chance of being killed yourself should increase. Basically a "3 strikes, you're out" kind of thing. After all. Serial killers/mass murderers tend to be the craftiest, and thus the prime people for the death penalty.
After all, if there were a prison break, and there were no death penalty. All the murderers that did enough to "deserve" death will be able to continue to kill, thus putting many innocent people in danger.
Here it is normally a punishment to dangle over your head. They believe if we know what COULD happen, we are less likely to do so. I guess it works to an extent, but most humans tend to have to learn the hard way to really get the lesson across.
I don't really like it, but it is sometimes one of the only options available. So I have to deal with it. So again, this is just an analysis from someone on the fence.