Benedict Cumberbatch is ''thrilled'' with 'The Fifth Estate'.

The 37-year-old actor plays real-life WikiLeaks founder Julian Assange in the upcoming thriller and he admitted while he enjoyed the role, he was ''terrified'' before he watched the finished movie for the first time.

He told the Independent Radar magazine: ''I'm thrilled with it. I'd seen it in the States and I was terrified.

''I cannot watch myself for the first time, especially playing someone who is so removed from me - because of everything, the appearance, the accent. Everything about him is different.''

And despite the film being criticised by Julian - who himself actually wrote to the 'Sherlock' star in an attempt to persuade him not to accept the role - Benedict has defended it against claims it is a character assassination.

He argued: ''I think [director Bill Condon] has made a beautiful film - it's incredibly balanced. It's entertaining as well as intriguing.

''And what it should do is ignite a debate - that's exactly what should happen. And hopefully it will do that.''

Whereas that movie had its own challenges, Benedict also acknowledged the difficulties of playing dragon Smaug in 'The Hobbit' trilogy after he filmed with the motion capture technology used by his co-star Andy Serkis' role as Gollum.

He explained: ''A serpent with cold blood and a backbone - who is twice the size of the Empire State Building, breathes fire, is 400 years old and lives on a pile of gold in the middle of a mountain - is a little bit difficult to bring any reality to.''