Didn't like the premise and some of the execution
Very minor quibble: In the beginning the main character receives enough of the drug to keep him human for 18 hours. That was what was available in a little cabinet. I'm sure 3 rooms over there were 150 more doses. And the recipe to make more. And the ingredients to make more. I'm just saying he probably could have bought himself a month or more easily.
Major Problem: There's a saying, "A bird in the hand is worth 2 in the bush." Why? Because you already have the bird. It will cost you to even attempt to get the 2 in the bush. In this film we are to expect that every character thought the best idea was "a bird on the other side of town in the direction of all the zombies that my friend swears exists, but even he's not sure, is worth more than 10,000 vehicles perfectly capable of getting them to safety.
Why was the helicopter so valuable? It couldn't go anywhere a car couldn't. It was short range, it required a very specialized skill, and it could only hold 4 people. Meanwhile every car, including the one they were in, was perfectly capable of getting them anywhere safely.
But let's say they wanted to be more physically removed from the zombies...get a boat! You will pass hundreds of them on your way to the helicopter.
Next you have these people convinced there's only room for 4, so everyone else will be left behind, and the Americans and the dumb b!^$# friend spend half the movie trying to kill the other survivors. Why? Because the helicopter, past 1,000s of viable vehicles, is apparently the only thing in the world that makes sense, and the 3 people in the know didn't bother at any point conveying the notion that they would take trips!
The motivations didn't make sense. If the Americans thought they were going to be left behind, why were they being allowed to come in the first place? Because of their awesome cower in a corner skills? Or perhaps their stab everyone in the back the moment they get a chance skills? Why are the boyfriend and girlfriend so dead set against saving the world? "You'll poke her with needles!" The b!tch didn't mind getting tested on when she thought it would help her, now the fate of humanity is on the line, and she flat out refuses, she'd rather live in a world of zombies than even set one foot in a lab?
Though I still enjoyed watching it. I don't have high standards for enjoying zombie films.