Jonathan Lethem is a powerfully good writer. Such strong stuff I have to take it in small doses. It took me several days to get through one of his novellas. I finished The Hardened Criminals in one sitting, but it's still a bit of a test.
Lethem was one of the inspiring forces behind the collection I am currently reading, The Secret History of Science Fiction. He speculated in an interview on what SF would be like today if Gravity's Rainbow had won the 1973 Hugo award, rather than Arthur C. Clarke's Rendezvous with Rama (also a pretty good book). He believes SF lost an opportunity to reward and promote literary SF, but chose the safe route.
I've read them both, and have to say I enjoyed Rendezvous With Rama but can't remember much about it, while I remember quite a lot about Gravity's Rainbow. Mostly I think I'd be better off reading more Lethem, but haven't quite gotten up to it yet.
The Hardened Criminals starts with its literal premise--a prison built from the bodies of criminals, somehow hardened and preserved so that they sort of live and talk, but are solid as rock. The son of one of the hardened criminals is put in the cell where his father is built in, as part of an effort to uncover a conspiracy. But there's quite a lot more to it, of course. Lethem gives you an insight on the thoughts and decisions of Nick Marra as he negotiates prison life in this very unusual prison. The state of the prisoners is explored in detail, but without diverting the story from the living characters. It's a great example of speculative fiction being used to explore an idea and bring it out in more stark detail.
Lethem has been feeling constrained by SF lately, and has been branching out. But I bet he never leaves entirely. I highly recommend this one, it will leave you thinking for a long time.