I don't care about other's opinions, they all try and compare it to the other 2 films but it's not. Think of it different.
No one knows what's going on and that makes it scary, the cat and characters were thought out in full depth and the heart warming story balances out the horror aspect perfectly that you actually care deeply for the characters and start to worry more for their safety.
A thing to understand is that horror films are not there for jumpscares and to scare you but to make your skin crawl, your heart beat fast and build tension that you would feel cold in a sauna. This film hit the mark.
There are moments unlocking new secrets about the aliens such as their age groups which makes the first 2 films more terrifying to think about.
I highly recommend, just ignore the concept of the first 2 films and enjoy.