Liam Neeson and Pierce Brosnan are phenomenal in their parts. It's a treat to see fine actors working off each other to create a duo in a film that's theme focuses around the true nature of revenge. The plot, however, is so simplistic it provides little to play against. The 'crime' is revealed slowly over time as Neeson and Brosnan reveal their roles in the North and Southern side of the civil war. If you like darn good acting this is the movie for you.
If you like a story with a clearly defined plot and ending I'm afraid this film will disappoint. The ending drove me mad. I hate slice of life films that leave me without a question to ask or an answer to the theme depicted.
I'm no expert on filming, editing etc. but it looked pretty good to me and the stark background amplified the rigid roles of the men involved.
If you like violence where the larger party of vengeful followers are picked off one by one -- this is for you. Me, I tire easily of worn-out plot ploys substituting for dialogue and storyline.