(243 chapters of the Rebooted version, which is the recommended version since it cuts down on irrevelancy)
This has an anime. The anime is a great indicator for whether you'd like the book or not. Only noticable differences between the anime and book is more of a focus on the side characters and more world building, which is a good thing. One thing to note however, is that in the book, after the stopping point of the anime, the tone gradually shifts to become more serious while still mantaining its light hearted nature. Its still comedic though.
Read this if you want (Slight Spoilers Ahead):
The story's pretty great and expansive as a slice-of-life. If you're into political dealings, you can examine the relationships between the nobles present in the story. If you're into leveling and growing stronger, while there is less of a focus on doing so, its still everpresent in the story. If you're into research and development of slimes, this is basically the godsent book for thee. Its light hearted and comedic, which makes the serious moments a bit more chilling.
Characters are amazing. All of the characters are being developed and fleshed out as the story comes out. The MC's is the most obvious, but there's changes in all of the important side characters and even some of the lesser ones.