Most people I know who finished it enjoyed it, but I also know plenty of people who couldn't finish it (which I understand-- the pages describing the broken tooth on Turing's bicycle as a metaphor for a substitution cypher were torturous. And tortuous.).
I mean, it's not high literature that scholars will be analyzing to death two hundred years from now, but Stephenson's books are generally creative and fun, and I enjoy them. OP's mom was probably at least half troll.