I had one major issue that jumped out as to why this was not a great movie: PLANTS.
A plant, in case any of you don't know the term, is when someone introduces an idea or object that will return in a later scene at an important moment. For example, if a character looks at an orange and take the time to put it in his pocket, that's a plant. Later in the, let's say, television episode, it will most likely come back into play.
Cowboys vs Aliens is loaded with plants. Way too many.
SPOILERS TO FOLLOW
Although, one could say that all of these examples are spoiled the minute they're planted.
Plant #1: Doc shoots his gun
Sam Rockwell, the local doctor/bar owner, has never shot a gun. A preacher suggests he learn. He gets a hold of a rifle and shoots at some bottles but hits nary a one. In a later scene he tries to shoot some bottles again and still hits nary a one. Guess what happens in the final battle scene? Did you guess? Correct! He shoots an alien right on the button in a lovely moment of deus ex machina. It's so predictable, I just sort of shrugged when it happened.
Here's how that could be fixed. Let's say he's got this gun and he shoots the bottles, doesn't hit them. Okay, we've been introduced to the idea that he can't shoot, and now we expect him to learn. Instead of showing him shoot at bottles again to remind us of the plant, let's show him shooting at a person in a battle, maybe that final battle. Maybe he misses and misses, and finally he sets up that perfect shot and he just knows this one will hit and the music swells and - he misses. Aw, hell. then, he flips around and BAM! He hits! hooray! It's his big moment, but it's not so damn contrived.
Plant #2: The kid with the knife
Early on, Harrison Ford's character, Dolarhyde, sits around with this kid and makes a HUGE deal of giving the kid his knife. Then, in a later scene, Dolarhyde takes the knife back, explains its significance, then hands it back to the kid. So during the big battle scene, an alien chases the kid, backs him into a corner, and we're sitting there waiting.... and waiting.... and waiting for the kid to remember that he has the knife. We know he has the knife because we were reminded of it, and because we keep seeing it poke out from his belt. So it's a boring scene because we're just sitting around twirling our thumbs while we wait for the kid to figure out what we already know.
Remember that example with the orange I mentioned up top? Well, in David Tennant's first full episode as The Doctor, he woke up in a bathrobe and found an orange in his pocket. He made an offhand comment about it and shoved it back in his pocket. Then he did some stuff. At the end of the episode, an Alien came at him. He had no weapon, and his back was turned to the alien. He reached into his pocket, pulled out the orange, and threw it at a switch that made the alien fall off a cliff. THAT is how you do a plant. You mention it, let us forget about it, then pull it out just in time, so we go "Oh hell yeah I forgot about that!"
If Dolarhyde had loaned the kid the knife in a casual way, or the kid had stolen it, or found it, or we at least weren't reminded of its existence, we might have had a chance to forget about it.
Plant #3: Resolved arcs
Every single character in Cowboys and Aliens gets a resolved arc. They all have something to learn, and without exception, every single character learns it. Not everybody needs to have closure, and after a while it feels too contrived when each person gets their learning moment.
In the end, I felt like a lot worked in this film. Like I said, I enjoyed it, but I also felt like it was a little too neat, particularly for a Western.
