I'm 36 and reading the books with my 7 year old right now. He's really into the graphic novels and the little sister books. He's in second grade and he really relates well to Karen. He's a very good reader so mostly reads them on his own but because he's interested I am rereading the books out of nostalgia. I'll probably still reading them when my daughter who is 1 is old enough.
Apparently they are still publishing Goosebumps books which I remember my younger siblings being really into back in the 90s and my son ordered some from his scholastic order. He'd been reading them at the school library.