Britannic starts off quite well, with relatively good effects and interesting characters, although its claim of being "based on true events" is very misleading, somewhat similar to saying that Men In Black was based on true events as Earth, where it was based, existed. The Britannic did indeed sink off Greece, although the sinking was believed due to a torpedo strike or mine, not German agents on board the ship as the film pretends. Too many facts are wrong in this film, either made up or worse still blatantly contradicting the real event - but taken as a work of total fiction, which it basically is, it is still enjoyable. That said, it just copies its sibling, James Cameron's Titanic, far too much - too many things in this film are copies of Titanic's plot, right down to the love story between two people of different classes - in this case German and British rather than First Class and Third Class. The film weakens noticeably towards the end, the special effects (which seem to have been quickly put together by the same effects house as for Titanic, but with little of the attention to detail) get a lot poorer, and the plot falls to pieces in its attempts to copy the Titanic formula. Watch it if you've nothing else better to do, but don't expect the plot to live up to the real event's promise...
Review of Britannic
