They were very unhappy about it, since the Act basically said that the British Parliament had the right to pass any law (including a law about new taxes) at any time, whether the colonists agreed with that law or not.
Since the colonists still had no representation in Parliament, this was yet one more motivation for the colonists to consider a rebellion, and a number of American colonial leaders began to advocate for such a rebellion against British rule.
why is this important: because the Americans colonist can stand alone without any help from the British.
I hope that I help you.