the novels are definitely better done! the first arc (the one that was adapted into the show) is probably the weakest in the series, and even then, the anime left out some important characterization concerning certain characters and left the ending confusing and weird. the second arc, restart, is set in another "death game" sort of style, but the third arc is where things really pick up and deviate from the original setup. like i said, there's some great world building as the series progresses, plus the survivors of the first arc go through some really good character development! way more likable now than before.

i'd say if you're curious, try giving it a go. if you end up getting into it, you can probably blow through all the novels pretty quickly. there's lots of fun side stories expanding on lesser characters too.