In terms of performance, I thought it was adequate, although it's clear that he's not as adept at speaking off-the-cuff as some of his predecessors. I expect his skill at these things will improve with time.In terms of message, I thought it was very effective. Bush clearly understood that he was being heard all over the world, and certain of his phrases (like his characterization of bin Laden and al Qaeda as "the evil ones") were clearly used more for their effect on foreign ears than on the US.
I agree with Alex -- I voted for Gore, and have my share of disagreements with Bush's domestic policies, but I think he and other members of his administration are doing an outstanding job in responding to this crisis.