As many have mentioned before, the documentary "Deep Water" is better at telling the story than this film, but "The Mercy" still has its merits. The movie looks great for the most part in its 1960's setting, and the actors all do their jobs. I particularly liked David Thewlis and Rachel Weisz in their roles. Colin Firth is also good, but looks like a sad dog for much of the movie, even before his character gets into trouble in the beginning and eventually sets sail.
The movie almost rushes through the intro, with rapid speaking lines and stressed scenes that don't feel all that natural. This is actually a problem all the way through, as it never slows down enough for us to truly take in the isolation and loneliness that Donald Crowhurst (Colin Firth, that is) must have felt in real life. We spend too much time on land and too little time at sea. As with many other films, it's hard to translate human thoughts onto the big screen ("The Old Man and the Sea" must be the classic example of this), and "The Mercy" fails on this note more often than it succeeds.
I do, however, still recommend the film, because it is still a good movie with good actors, and it's worth watching. It's just a shame that it doesn't reach its full potential, with a fascinating story such as this one.
I haven't seen "Crowhurst" (produced at the same time as "The Mercy", but by a different studio), but I've heard that that one is a bit better. In the end, "Deep Water" seems to be the best choice, however.
UPDATE (8 November, 2018): I have now seen "Crowhurst", and I am not sure if it's better than "The Mercy". I gave both films six stars. They are very different, however, as "Crowhurst" is more of a low-budget, theatrical art house film. It is also a character study, rather than a story-driven movie. Because of this, I think both films are worth watching, for their own reasons. "Deep Water" tells the story better than either of them, however and is indeed the best choice to watch.
