Like everyone else probably has already said, there is something of the Coen Brothers about this film, but not in terms of humor or oddity, but rather in its stripped down violence that worked so well in Blood Simple. The plot here sees a homeless man learning that the man who murdered his parents has been released from jail. He sets out for revenge, but the attempt goes badly, putting his estranged sister and family at risk.
Starting out mostly in wordless scenes, the film draws us in with Dwight revealing a lot of his life and what led him there, all with little touches and moment. We don't fully understand the ins and outs of it all, but the gist is clear and it is engaging. The steady pace of the start continues throughout, and it works well to produce tension and build-up within scenes, but also across the film as a whole. The stripped down feel to the writing, soundtrack, and production all add to that sense of tension - it doesn't feel forced for flamboyance or excessive (although the closing scenes maybe do a bit, to their slight detriment). There isn't a 'side' really, although of course we follow Dwight as our way in - but it is the spiral and lack of choice that draws the film along just like it does to him.
Blair is the star here and he holds the film together. He is convincing in his simplicity, and delivers an engaging character whether he is on the beach at the start, making bad decisions, or dealing with a mess he has no way out of. The supporting cast are all good (and benefit from a lack of 'faces'), but it is Blair's film throughout. Writer/director Saulnier has a deft touch for tension, with good camera movement when it matters (tracking what isn't visible for example), as well as allowing nothing to happen at times when so much is at stake.
Blue Ruin was a surprise find at a time when I knew nothing about it but the running time fitting my evening. It turned out to be a gripping but sparsely populated film, which played to its strengths from start to finish.