Takashi Yamazaki is one of a handful Japanese directors who can make a proper blockbuster. While his films fall short of being true masterpieces, they offer solid entertainment while staying clear from being too generic. Parasyte fits right in with the rest of his work, making it perfect filler.
The film is clearly based on a manga/anime, though you don't need any prior knowledge to watch it. The setup is very simple, with a weird species of parasites on a mission to dominate mankind. One of the creatures fails to take over his host's brain and ends up as his right hand (literally). The two of them learn to live together and become the unlikely heroes of the story.
The monster design is pretty outrageous, but hilarious. The film is also quite gruesome for a blockbuster, but nothing a regular horror fan can't handle. Performances are solid, with Shôta Sometani as the charismatic lead, the cinematography is slick and the visual effects on point. I really had a lot of fun with this one, it won't be long before I give part 2 a whirl.