Let's get the annoying details out of the door:
- isekai: a class of 25 students + 1 teacher got isekai'd by a mysterious incident into a fantasy world
- main protagonist, a female student, wakes up as a newborn spider (commonly referred to as Kumoko (kumo means spider in Japanese, -ko is a suffix for girl)
- Kumoko tries to survive in the Labyrinth where everything tries to kill her, including her Mother and siblings
- for some reason things in the new fantasy world is game-like, with skills and stats
Except it's not your typical isekai or your typical fantasy.
- The novel switches between several reincarnators' perspective. Even in the same event, different reincarnators see things differently, think of things differently, giving drastically different taste and feel.
- Main characters were given a lot of room for character development. Each of them feels unique and memorable.
- As of the latest WN chapter (2019), most underlying mysteries of stories were resolved and explained in a way that is consistent with established story. For example, the reason why other monsters hate Kumoko so much, why a hoard of certain monsters attack Kumoko, or the mysterious existence of skills.
- In general, the story feels well-planned. There are causes and effects.
- The story doesn't feel sugarcoated or fan-service-y. In many conflicts, the story is shown in both parties' point of view. Many "typical fantasy events" are shown in a different, more realistic light.
If you're interested, be warned. There are a crap load of Kumoko's internal monologue and thoughts (and occasionally other people's thought as well). As a result, the pacing is quite slow.