I didn't really like the movie. Certain parts of it was well done, but there are some glaring issues that ruined my suspension of disbelief.

For example, early in the movie we got a shot of John's character's workshop, and there's this whiteboard with the most basic information about the monsters written on it in large bold letters. Your character has masterfully survived for over a year under constant threat from these monsters, and you have to write down that the creatures are blind? Who is this even for other than the audience? It's such a lazy way of conveying information and disrepectful of your viewer's intelligence.

Also, the ending was pretty ridiculous.

*spoiler warning*

The fact that these monsters are susceptible to small firearms (even if they have ARMOR as the whiteboard reminds us) makes the premise that they overran all the world's militaries in a few months pretty unbelievable.

More spoilers:

I think the movie tried to show that they only opened up and became vulnerable when they heard the feedback sound from the hearing aid.

The movie didn't really go on about how they defeated armies, but really they only have to kill the farmers, everyone will eventually starve if they can't grow food.

Moving this video to Sarzy's personal queue. It failed to receive enough votes to get sifted up to the front page within 2 days.

Yeah, the whiteboard wasn't the most elegant way to convey that information, but it's quick and efficient, and it's still better than having one of the characters flat-out say that stuff even though they'd all know it already.

As for the second issue, as greatgooglymoogly mentioned, they're only able to shoot the creature because of the dumb luck of the frequency of the hearing aid weakening it and causing its armour to pop off. Deus ex machina, maybe, but the film spends enough time planting that seed that it doesn't feel too blatant.

*promote

Self promoting this video and sending it back into the queue for one more try; last queued - promote requested by original submitter Sarzy.

Since we're in spoiler town, any guess what the creatures were meant to be? They seem too dumb to be Aliens. Maybe subterranean bat monsters from the center of the earth?

Pure speculation (I don't think the movie gives any hints as to their origin, though I'll have to look out for that when I watch it again), but my theory is that they were brought to Earth by a race of intelligent aliens who want to wipe out humanity, but without the destruction of a bunch of bombs.

I think they are the mutant result of what happens to a person subjected to years of dubstep.

The face part opened up, but the "ears" pop open and uncover whenever they're trying to listen closely.

I any case, armored just means they have some resistance to small arms fire, like the bugs in Starship Troopers or xenomorphs in the Aliens universe. Unless the monsters in this movie are covered in adamantium, I find it hard to believe that they can wipe out the world's militaries in such a short time.

Also, they would have to defeat the world's armies first, as securing the food supply would be one of the top priorities of any army. No military is going to sit around waiting to slowly starve to death.

Using a white board or having a character flat out say the information are both bad storytelling. A better filmmaker would have been able to convey such information organically. At least the saying it flat out approach could have been worked into the movie as an old emergency warning broadcast, or early on in the outbreak when people could conceivably still be ignorant.

Also, I didn't think the weakness to hearing aids was that blatant. It was certainty better than the water vulnerability of the aliens from Signs. It just felt silly that the all the world's militaries with all their armor piercing weapons couldn't do much to these monsters but a wounded mother with a shotgun and her child could.