In a recent interview with Collider
, Hugo Weaving, the voice of Megatron in the live action Movie series, has revealed how he very nearly turned down the role and how he felt about being the leader of the Decepticons. In a frank and honest response, he reveals that he in fact never went on set and has never met Michael Bay - he had minimal involvement in the project. He goes on to say while he does not regret doing the role, he regrets doing something he felt was meaningless (though he does not mean that in a nasty way).
Check out the full interview
here which also talks about Weaving's role in The Hobbit and Captain America.