Peter Ericson’s review published on Letterboxd :
The idea of pitting cowboys against aliens has potential, but "Cowboys & Aliens" only partially succeeds in extracting the gold nuggets. It doesn’t have any particularly memorable qualities and ends up being a mediocre realization of an interesting concept. All things considered, however, the movie is a fairly pleasant diversion with a promising beginning, a weak middle section, and a satisfying ending.
About halfway through "Cowboys & Aliens", the film begins to lose momentum and spiral downward, starting with a scene in which the characters are gathered around a campfire. What transpires in that scene is jarringly ridiculous and raises a few problematic questions in the mind of the viewer. The scene in question is followed by some heavy-handed exposition that reveals the aliens’ real reason for having come to Earth. Fortunately, the movie picks up speed and energy in the climax.
The aliens look otherworldly and threatening enough, but they are not particularly original in appearance. While generally solid, the effects work fails to be entirely convincing in the scenes in which the creatures are running around attacking people in broad daylight.
Perhaps the film’s biggest problem is that there are no characters for the viewer to really care about. One becomes most invested in Emmett Taggart (sympathetically played by Noah Ringer), but most of the time he just reacts to what is happening to and around him.
Director Jon Favreau and the posse of screenwriters involved here (Roberto Orci, Alex Kurtzman, Damon Lindelof, Mark Fergus, and Hawk Ostby) wisely choose to give the picture a consistently serious tone. I don’t think a more tongue-in-cheek approach to the material (the film is based on Scott Mitchell Rosenberg’s graphic novel of the same name) would necessarily have made for a better movie.
One of the things I like about the film is its strong atmosphere. Matthew Libatique’s warm lensing, the period details, and the locations make "Cowboys & Aliens" a treat for the eyes.
Daniel Craig is quite good in the role of Jake Lonergan, bringing nuance to an otherwise rather stereotypical character. Harrison Ford probably could have played Woodrow Dolarhyde in his sleep and doesn’t seem to put much effort into his performance here, but he is always watchable. Playing Ella Swenson, Olivia Wilde gets the job done, nothing more and nothing less, although she deserves credit for her composure in what must have been an awkward scene to shoot. Sam Rockwell, Clancy Brown, Paul Dano, and Adam Beach acquit themselves nicely in supporting roles.