So if you're interested in reading this either from watching the anime or hearing it from your friends, well here is a review.

The manga for Parasyte was released between the late 80's to mid 90's

These parasites who appear in the manga, are aliens who take over people and well in similar stories like this, eat and kill people. Shinichi happens to be one of them who get attacked but survives (like any protagonist would do.)

As you read through the manga, you see how Shinichi's life is affected by these parasites, his character changes, his relationship among his family and friends also change even to one of them concerned for him.

I really recommend you read this, it's not a long story and it's not a short story. From what I see the story doesn't drag itself, it continues and the pacing is good.

Now for the people who watched the anime you will notice this:
While reading the manga you see similarities and differences.
As the anime basically modernizes the story, in the manga you'll see Migi reading a textbook or encyclopedia instead of using a computer, clothes are different and there's more scenes added and scenes altered.

Plot and characters are the same.

Some scenes from the anime are altered for example: There is a part where Shinichi is having a conversation with Satomi then out of nowhere Migi turns into a penis.

If you like sci-fi, aliens, horror, Prototype, the anime or a good story with characters and development (because who doesn't like that?) then give this a try!