Yes, there is heavy use of cringey slang. Most characters are indeed shallow and dumb throughout. These seem to be the main reasons for such low-star reviews from students who didn't like reading it in their English classes. The style definitely takes some getting used to & there isn't much character development or backstory, but Anderson's message is more timely than ever.
He is a bit "heavy handed" in his warnings about technology - but he wrote this in 2002, before iPhones, smartwatches, & social media, just as personalized data was beginning to be collected for targeted online advertising. The ads mixed in between chapters are intentionally disruptive, constantly intrusive, just like the ones we scroll past.
Anderson paints a world teetering on its last leg, irreparably polluted, radioactive. The characters aren't equipped to realize it: they're too busy buying, they accessorize their lesions, they don't wonder at the hackers' motives, they're not even aware of the other nations threating them with war.
Anderson isn't "making fun" of the young generation for their consumption, he's warning everyone (the adult characters use slang, too) not to be apathetic pawns of corporate greed. He's showing what a consumerist society might become without some standards.