This is one of those movies that polarises opinion. You either get it and love it, get it and hate it or don't get it at all and wonder what the point of it is.
My advice is if you haven't seen the film and intend to do so, DO NOT READ THESE REVIEWS. Far too much is given away in some of them. It is much better to sit down and watch it with no concept of what is to come. Make up your own mind, one opinion is worth no more than the next, despite what some self-aggrandising critics and reviewers seem to think.
If you haven't seen it, this is all you really need to know. Troubled single mum and coffee shop waitress Melissa George is persuaded by an admirer to join him and some of his friends on board his yacht for a day's sailing off the Miami coast. While at sea, a strange storm capsizes the yacht with one of the party missing, presumed dead. When a passing cruise liner picks them up, they believe they are saved. But once on board, George's character gets one of those "deja vu" moments...
***SPOILERS***
As others have said, this is a film which rewards a second viewing. For instance, the drum in the ship's ballroom is exactly the same as the drum being used by the boy at the car crash scene, something I only noticed second time round. This sort of attention to detail adds to the "dream-like" quality of the story.
Of course the big flaw is the fact that George's character seems to remember certain things but not others. This appears to be explained away by the fact that when she falls asleep her memory is in effect "re-set" and she can only recall the odd moment through deja vu. Convenient! This happens once on board the yacht when she dreams about being washed up on the beach and once in the taxi on the way to the harbour, which explains why she doesn't properly recognise her fellow passengers.
The role of the cab driver as gatekeeper isn't exactly subtle, but it's a good line when he says "I'll leave the meter running - you do promise you'll be back..." I saw on another website one viewer asking why she didn't just get out of the taxi and go the cinema to break the cycle. But of course the point is that her single motivation is to try and stop her son's death. The cab driver himself taunts her at the crash scene by saying there's nothing anyone can do to bring the boy back and she clearly resolves to re-board the yacht to prove that she CAN.
The references to the mythology explicitly covered in the movie courtesy of the helpful poster on board the ship are well covered in other reviews. This is her living hell as punishment for killing her son and she's destined to go through it for eternity. A great idea, although the execution is far from original. The Spanish thriller Timecrimes (highly recommended) explores the same time-loop idea, while Memento is similarly layered and of course there are many similarities to The Shining.
If you've ever watched the old Dawn French series "Murder Most Horrid" there is an episode with Jim Broadbent where her character creates a time machine and uses it to try and stop herself from killing her husband. Some of the ideas are incredibly similar to what is seen in Triangle. We see the same conversation and action take place several times from different perspectives. In Triangle this is taken to extremes and is perhaps one of the movie's biggest flaws. It feels a bit like the director is trying to pad out the movie by showing us the same thing again and again in full.
But Christopher Smith deserves credit. This movie is a quantum leap forward from previous efforts Creep and Severance. Many people will hate it as the litany of one star reviews shows and I can understand why some viewers would feel frustrated by the story. But I always feel any movie that makes you think and discuss afterwards should be applauded. For me it has a satisfactory conclusion and there are some genuinely shocking moments (the pile of bodies on the ship being one that particularly stands out).
The sound and picture quality are excellent, George is solid and occasionally very good in the lead role and while there are a couple of dodgy accent moments from the Australian cast playing Americans, overall the acting and script are sound. It's not a traditional horror movie, far from it, it's much more of a psychological thriller with the odd bit of gore. I very much enjoyed it and would recommend it to fans of this genre.