It starts out like a regular Western you've seen tons of times before & suddenly everything is interrupted by aliens. I think they did a really good job of having the cowboys deal with the aliens in a realistic way. It was interesting watching the 3 levels of technology that existed at the time interact. I liked the cowboy movie substitution where instead of the horse running alongside a train, it's an alien ship. I also liked that the Native Americans were not eager to help.
Daniel Craig is the toughest cowboy ever but he was also able to be caring. Harrison Ford was a gruff general who had the best lines in the movies. When he was being incredulous at the reason the aliens were there & when he was talking to a young boy. The preacher also had some good advice in the movie: "God don't care who you were, son. Only who you are." This is because there is an underlying story of redemption. There is also a lot of heroic self-sacrifice from almost everyone in the movie. As much as I dislike Olivia Wilde, she was adequate; although I'm pretty sure she used a body double for her revealing scene. Nobody was campy, they all played it straight.
Of course there were a few clichés in the movie, both action & cowboy, but I don't think any of them were glaring enough to ruin the movie. I liked the I think having the aliens was a good way to make a western for modern audiences. I feel like renting the westerns that the filmmakers watched while they prepared for the movie.