The advantage of the Zero was soon lost as the Americans introduced the better Corsairs and Hellcats to the services. The Japanese weren't able to match either of these aircraft.
One of the reasons the Zero was so agile was because the designer set to make it as light as possible. It was constructed out of thin sheets of aluminum. Also it had no armor or self sealing tanks. It was also underarmed compared to its American adversaries.
As the war progressed, these disadvantages of the Zero were exploited but it was still a dangerous opponent in the hands of a capable pilot.