I do not disagree with what the first answer says, but I would argue that the purpose of the Declaration was not merely to inform people of why the American colonies were trying to become independent of Great Britain. Instead, it is a work of public relations -- it is a document that is meant to make people dislike Great Britain and support the colonies.
I say this because much of the document is devoted to a list of complaints about the King. These complaints are put in ways that are clearly meant to persuade an audience that the King is really in the wrong. They are not meant to inform an audience as to both sides of what was really a very complex story in which both sides could be blamed for the problems that occurred.
Because of this, I see the Declaration as more of a press release than a document meant solely to inform.