When you have an organization that can reach its tentacles out around the world and indoctrinate people long distance, they are the worse kind of threat. To compound their evil they have no regard for human life and will rape, pillage, and kill anyone who does not conform to their beliefs. Their barbarism is on a level mankind has not experienced in our lifetime. They are way beyond dangerous.
After seeing the large amount of documented attacks and terror, there is no question that ISIS is a threat. However, many people in the west fail to realize that ISIS is a threat mostly to peaceful and law-abiding Muslims. ISIS attacks Muslims in their home countries who they feel do not follow their fundamentalist brand of Islam. They also work to discredit Muslims worldwide to instigate holy war against the religion at a whole. We should not give in to their terrorist tactics.
Destabilization of regimes, torture and murder of innocents, mass displacement and the financial burden borne by those tasked with controlling the threat from ISIS are all genuine threats to freedoms and economies the world over. Terrorists can achieve their aims by doing more than blowing up cars and buildings. Disrupting lives and ways of governing can be just as effective.
ISIS has already shown the world what they can and will do if they choose to. They have carried out numerous attacks, and convinced others to carry out attacks in the name of ISIS. There is no indication that the group is not serious, and they should be dealt with accordingly.
ISIS aren't a threat to the freedom of our planet, although their aims are to basically take over our world to purify anyone who are not Sunni-Islamic believers. Which so far they haven't acomplished much.
Although their main ways of recruiting and empowerment is propaganda through the media. So no.