This is difficult. I oppose the death penalty outright, and I think that Saddam should have been sentenced to life without hope of parole.
There is a tendency to focus on the immediate and not the historical context - it's a human trait. Moreover, there is a fixated anti-Americanism at the moment amongst sections of the left. It is regrettable, as it confuses the issue on two points.
Firstly, there were a lot more charges against him that must now be dropped under Iraqi law as he has been executed, not least Halabja, which has caused consternation amongst the Kurds.
I have more problems with the manner of the trial than the sentence - there is a need to show that justice is blind and even-handed, as represented by the famous statue, as well as its wielding of a sword. Justice not only needs to be done but needs to be seen to be done. Saddam was clearly guilty of all the charges laid against him; his immediate coterie were as well. I would raise, though, the example of Hjalmar Schacht. I am not fully familiar with his case, and so I apologise if my facts are wrong or I cause any offence, but he was acquitted of Crimes against Peace at Nuremburg in 1946. He was relatively low-profile, and I do wonder if the example given by Saddam's trial might lead to a similar figure in the Iraqi Ba'ath party being found guilty when they might be more deserving of an acquittal.
I'm afraid the spectre of Operation Paperclip raises its head here.
One of the arguments often used, by myself amongst others, is that the death penalty encourages a retaliatory attitude in a society. In Iraq at the moment, this is not really an issue. However you describe the conflict, there's an awful lot of retaliation going on already.
There is also the argument that all life is sacred and that there was no necessity to execute Saddam, and so it could have been avoided, which comes into play here.
I think the pictures and sound of the execution are behind a gut revulsion on this one.
Personally, while I regard both the act and manner of Saddam's execution as wrong, his crimes are far, far worse.