One can make a case and argue that here are some freedoms/liberties that have been severely altered or changed since 9/11:

Freedom of Speech
Freedom of Privacy
Freedom of Information
Right to a Fair Trial
Freedom of Association
Right to Due Process
Freedom of Economic Liberty
Equal Protection Under the Law
Freedom From Unreasonable Searches

Effective? You be the judge.

Has terrorism gone away?

No.

There are and will be way worse things than a plane flying in to a building and nothing we've done so far to change that.