I usually try to avoid political discussions but I believe the war was illegal.
Why? Because there was no justification or reason to attack. I dont say it was bad/good or morally correct/incorrect.
I say it was illegal.

For example:
You see Mr.X stealing 1000$ dollars from your car. You cant prove it but you are caught in an attempt to *get the money back*. However that can seem as stealing, thus illegal.

Personally I dont believe human rights violations in Iraq was the reason of the atttack, just an alibi. What ever was the reason, it was not for good of Iraqi people.