Absolutely loathsome, and not interestingly so.
Despite wordy descriptions of the countryside, TEDIOUS details on guns & ammo & cleaning thereof--not to mention jarringly specific brand and author name-droppings (first Turtle "is wearing Levi's [sic] over black Icebreaker wool tights" and then she's "pulling Carhartts over her Smartwool long underwear"; Middlemarch, Marcus Aurelius, Proust and all sorts of high-end books are mentioned) the descriptions were confusing and monotonous, and there was was remarkably little sense of place or palpable difference in the characters. The author was showing off his knowledge of plant vocabulary and literature (and, oh yes, guns, always with the guns!) and sounding 'poetic', but there was not enough interiority of character or believable psychology--or even exterior description--for me to distinguish between the 2 boys, or the 'nice' hippie-stereotype teachers/mothers.
It's not that I don't believe that backwoods monsters like the father exist, or that his daughter could be profoundly abused and also love him, but somehow I didn't buy the dialogue, neither the ostensibly 'humorous' banter between the boys, nor Turtle's internal monologues of self-loathing.
Beyond a basic need for narrative closure (wanting to see if she got out of it alive) I stopped caring, and despite being a person who loves 1) words 2) learning about areas beyond my scope through a narrative story 3) medical/surgical descriptions, I found the endless guns and dank plant life unutterably wearisome (I started skimming over these early on) and the surgery/medical descriptions callous, revolting and monotonous at the same time.
The author perhaps was attempting to humanize his anti-hero (or promote his own libertarian ethos, or add interest in the story?) by inserting stuff about climate change, hippy pot-growers, capitalist off-the-grid techies, which all came off as both too specific and too generic to be anything other than banal, patronizing stereotypes.
When it all ended it up in a shoot-em-up teen-prom-party with a super-hero 'survivor' girl saving the day (lots of guns, lots of shooting, but boring to read because it was actually very unclear who was where, who was doing what; this was also true of the foul sex scenes, which were sadistically descriptive yet oddly unclear, though NOT because the author was drawing a veil), I guess that was not that surprising. Or that cathartic.
And don't get me started on the annoying use of the present tense. It seems to be a fashion these days, to evoke "immediacy" or some crap like that.