Heavily flawed 2nd half
Once we are introduced to the people on the harbour it raises so many questions. Have these people not worked out to use a boat and maybe cross over to the island on it? The little deaf girl worked out to do this minutes after arriving, and these people had presumably been there long enough to set up an ambush. Also their plan was to kidnap the girl in front of one might assume her dad, when he can put them all in danger at any moment by opening his mouth or making a noise, as can the girl? Which is funnily enough what happened straight after. Did they not see that coming? I mean seriously how did these people last this long when they come across as extremely dumb?
Not long after we learn that the aliens can't swim. From knowing they can't swim and can be manipulated by sound it shouldn't take much to devise a trap for them. Honestly when you give the aliens these sort of weaknesses you start to wonder how there aren't more survivors.