These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Also, there's some room for uncertainty regarding whether the aliens are truly replacing the originals, and taking their memories is merely useful for blending in, or if they actually see themselves as merging with the original individual in a symbiotic relationship. This can make the aliens either a case of Always Chaotic Evil, or simply Blue and Orange Morality.
"Funny Aneurysm" Moment: There's a moment early on in the 1978 film at a playground where a priest (likely having become a pod person) is on a swing while staring at small children who are playing. Suprised 4Chan hasn't hasn't picked that up yet.
The priest, incidentally, is played by Robert Duvall in a cameo.