The movie itself and the acting are just fine. Having one of the two main characters being blind at the start of a zombie plague is something different. Bad enough to be blind but during a zombie attack, that would just plain suck. Talk about terrifying.
My only real problem with the movie is that in every case a decision could be made they made the worst one possible. First off, at the start she fires 4 rounds from her semi-auto pistol and says she only has 2 rounds left. Yes, there are 6 rounds magazines but this is a police primary weapon, not a sub-compact. Possible sure, but not terribly probable and not a spare magazine or round to be had.
Speaking of which, at the farm house two zombies/bodies are present which would apparently be the husband and wife. He's in the tub having shot himself and the revolver is still in his hand. She's got 2 rounds left but does she take the pistol, nope. She covers it and him with a sheet. Nor does she look for any more weapons or ammo around, on a farm.
Now they are determined they have to get back to the ambulance because apparently there are no vehicles on this farm at all. Not that they check. So she tools up with an ax for him (who's staying behind) and a machete for her. Now the first time he uses the ax, he doesn't accidentally lose it, he leaves it behind. The first time she uses the machete, she leaves it behind. She empties her pistol and throws it away. Later she actually gets the farmers pistol, still doesn't look for more ammo and throws it away as soon it's empty.
That's just the first half of the film.