This is what a horror movie about spiders should be like. For the first hour or so everything works, it feels well put together, and the soundtrack only compliments this.
The spiders are well done, and there is some genuinely frightening jump scares.
It entire production takes place in a apartment block in Paris. It feels isolated, dark, grim, and poverty stricken. At times, it felt like the same isolation one would get watching the the first Alien movie.
However, whilst the movie is well made, the third act is difficult to take seriously. Sometimes less is more in this context. People in an apartment block fighting for their very lives was interesting, until it became silly and cartoonist.
That being said, the first hour is the best bit of horror you're likely to see this year.