Read up to 52% plus the end 5%. Kudos to the brilliant evocative cover of the 2010 Penguin Modern edition. 

Basically the story reads like de Sade fanfiction and Alice in Wonderland had a book baby, in the style of Candide's philosophical journey.

Practically, the core mystery of the infernal machine is crushed under the dull mindlessness of Desiderio's internal monologue and a series of dull, if grotesque, encounters - aesthetically similar of Candide, maybe? But in nature more Lolita.

There is no character growth, very little character work to speak of in general and worst of all - it's all filler. If you take the beginning of Desiderio's journey and his arrival at the endpoint and delete everything in between, I'm not sure much of the story is lost, because there is a lot of repetition and the episodes appear crushingly pointless.

As it stands, the mystery is in the last 5% and it is that

the infernal machines are volunteers fucking continuously until they explode into energy, which Hoffman uses to affect/change/stop time.

however up to this rather innovative idea Desiderio spends the book engaged in a Candide-like journey with the dullest 'autobiographical' reflections - peregrinations and reflections that, by most appearances end up meaningless intrinsically and plot-wise. Of these meaningless encounters that didn't affect the plot, make a philosophical statement or create some innovative literary sequence, a particular highlight is that

Desiderio spends some time engaged at some point to a 10yo and they perform several sexual acts, not including penetration. Why did that need to be in the book? Not only was it grotesque - it was useless.