Too long? It's an epic, says Transformers director

Either way, the special-effects blockbuster is out in the United States on Friday and is expected to take the box office by storm.

"I never read critics, they can say whatever they want. It's all about the fans. I think it's a real epic movie," Bay told AFP ahead of a preview of "Transformers: Age of Extinction" on Thursday evening in Miami.

Bay, 49, has directed all four installments of the popular franchise, about huge robots that turn into cars.

Known for big-budget action movies such as "Pearl Harbor" and "Armageddon," Bay said that bringing the film -- which involved the collaboration of 4,000 people -- to the big screen was a challenge.

"It is a very, very complicated movie," he said.

In the latest "Transformers," Mark Wahlberg replaces Shia LaBeouf, star of the saga's three previous installments, as the leading human.

"It's nice to freshen it up, changing out the cast, giving it all a new life," Bay said.

The cast, which also includes Stanley Tucci and Nicola Peltz, turned up in Hong Kong last week for the movie's world premiere.

The city provided the spectacular backdrop for much of the film, which depicts the latest scuffle in the eternal battle between the Autobots (the good Transformers) and the antagonist Decepticons.

Bay added that he gets the greatest satisfaction from the series -- which has grossed billions of dollars at the box office -- traveling the world meeting fans.

"We just were in China, we were in New York, there are fans around the world for this franchise" Bay said.

The director, known for his trademark blockbusters, did not rule out the possibility of getting behind the camera for a fifth installment of "Transformers," which was originally based on the popular children's toys.