Can Islam take criticism?

It seems that no one can say a negative thing about Islam without receiving a death threat or some muslims running riot. Lets look at some of these events:

The pope QUOTE

During a speech in Germany, the pope QUOTED the 14th century Byzantine emperor Manuel II Paleologus, who said "Show me just what Muhammad brought that was new and there you will find things only evil and inhuman, such as his command to spread by the sword the faith he preached." The pope made it clear that these were not his thoughts and clearly said I QUOTE. This caused an uproar among muslims, and the pope issued an apology regretting even referencing the emperor.

Lets see how the muslims responded:

These pictures are of a small protest outside a catholic church in London courtesy of this blog. These muslims are offended by the pope quoting someone, they say worse things in return! Does this seem like an appropriate response? "May Allah curse the pope" and "pope go to hell". So much hatred! If they think the pope is wrong, shouldnt they be praying for the pope instead?

A new group called "The sword of Islam" contacted reporters and said it had fired gunshots at a Christian church in the Middle East during a demonstration over the comments. We want to make it clear that if the pope does not appear on TV and apologize for his comments, we will blow up all of Gaza's churches,"

In Africa, a nun was shot and killed, with indications the attack may have been a reaction to the statements.

One muslim said: If this person were really someone reasonable, he would not agree to remain at his post one minute but would convert to Islam immediately,"

Dont muslims understand the concept of free speech? If muslims do not like some peoples thoughts on their religion then they should prove us wrong with good deeds not with death threats and fear.

Is Islam peaceful?