The basic premise isn't anything exceptional or noteworthy, though it isn't bad in any way either; the show opens up with a normal teenager waking up and realizing that his arm is gone, and in its place is a parasite (roll credits folks).
The show basically covers the dynamics between the parasite and the student, exploring how parasites are slowly taking over the world, melting into human society and the contrast between them and the humans (whether as a community or as a species). The contrast is generally well done, but becomes less engaging as the show progresses due to a lack of any real complexity among any of the parasites (for the most part) and completely among the humans.
This makes sense in the context of the themes, but means that the characters are simplistic and one note, becoming less engaging as the story continues.
The themes are quite interesting and compensate somewhat for these flaws, discussing how humans are in this setting no longer at the top of the food chains and how the parasites attempt to coexist and cope with humans for survival.
The show delves further and discusses how humans aren't mere killing machines among the parasites, delving into all sorts of different perspectives among the parasites and among the humans.
Problem is that that is exactly what the show does wrong. The themes are well-fleshed out and very interesting, but the plot is incredibly simplistic and incredibly reliant on the themes and the audience being completely engaged with them; once you delve further, the plot is filled to the brim with plotholes and flawed logic, and becomes less consistent and weaker as the show progresses.
The way the manga was adapted takes a good chunk of the blame, since the internet being present yet no one knowing about the parasites is in itself a giant plothole that is increasingly difficult to suspend disbelief for as the show progresses. The manga took place in the 80s, at a point in time where the internet was non-existent and as such it would make sense if parasites took time to be discovered. This gets worse as the show progresses, and is incredibly hard to ignore.
The artwork is pleasant to look at, though not as fitting as the manga's artwork. The animation is above average but nothing particularly special to look at, fitting the show but fairly low quality by Madhouse standards.
The voice acting is solid and consistent throughout the show, and the sound effects do not disappoint either.
Here we get to yet another problem the show faces; the soundtrack is generally very poor with very few standouts. I don't know who had the bright (read: stupid) idea of putting dubstep in the soundtrack, but it doesn't work and ruins immersion completely in certain scenes, which is a shame because this show has plenty of amazing moments.
The characters are generally unremarkable and forgettable, with character relationships being very forced, unnatural and forgettable for many. The show is fairly good at developing the interesting dynamic between Shinichi and Migi, and this is easily the best part of the show and the most entertaining one to watch.
Most of the characters are poorly developed, with very few receiving anything resembling development other than the main leads.
Overall, Parasyte is a show that does it's job and is a solid time waster for those looking for something thought provoking and distinct from most anime.
It's a far, far cry from perfect though, and the show is very inconsistent or even weak at certain parts.
Nevertheless, there's something in it for everyone, and it's highly recommended to give it a shot.
