By the way, you haven't explained why do you think the story is trash...
Okay, I'll bite and attempt to explain it to you.
The basic premise, a machine that can make you dream what you want and control said dreams ends up being addictive even after it ruins people's perception of dream/reality, is interesting. It has promise and potential for some good nightmare fuel. However, it all comes down to execution and delivery. This is where the story fails.
My chief complaint is that things progress too slow, presumably because the author wanted to cram in as many sex-scenes as possible. This also ties into the lack of variety. Everyone has the "same" dream; sex. And while I get that they're horny teens, I'd like to see some different dreams and how they'd turn into nightmares, both as "dreams" and when the machine user's try to enact their dreams in reality. I'll use the school nurse's arc to make my point.
In the manga, the machine is used on her without consent while she's sleeping in the nursery. Great move, Mr. protagonist. More on him later. Anyways, it's a wet dream, cliche about the sexy, mature nurse fucking her student(s). The plot drags along, showering us with sex scenes until the dreams bleeds over into reality. The nurse is addicted, acts out her fantasy and it ends (at the time of this writing at least) with her getting busted by another teacher as a bunch of students are essentially gang raping her. In her dreams she could have all the pleasure in the world, and control the dream. Reality is a different beast (pun intended).
Instead of this, I'd accelerate the plot more. So we'd get to the gang rape scene at school earlier and we can close off her arc. I'd close it off with her loosing her job and getting arrested for having sex with minors. This breaks her mind, since rape was never her dream, neither was facing legal consequences of her actions. It can be left open to interpretation whether or not she can "get clean" since she's freed from the machine and in jail. Basically, less horny, more horror.
Variety is the spice of life. So, I'd have more dreams that aren't just about fucking around. Getting perfect grades, having great friends, being #1 on the team, being a hero, standing up to bullies - the possibilities are endless. And since these are dreams, things the characters hope and wish for, the horror becomes extra gut wrenching when these dreams turn into nightmares because reality comes knocking. Lives ruined, fates worse than death kind of thing.
Our lead character isn't that great either. His motivation to make the machine in the first place is to have lucid dreams of the girl that rejected his confession. If this isn't bad enough, he's dense as a supermassive black hole; lending the machine to others, making more machines to satisfy demand, and loosing track of the machines in circulation. His stupid ass even asks one of his friends to dream of his crush getting fucked and use the modified version of his machine to record said dream so he can watch it on DVD later. True love is when you make porn of your lover, without them knowing let alone consent. As much as I'm for flawed protagonists, it gets very hard to root for this guy.
Modifying the machine is interesting and could push the plot forward, as well as raise the stakes. Video and photo's taken from dream recordings help further blur the line between dream and reality (photos/video are seen as proof of reality after all). Sadly, it just further extends the sex more than anything else. I'd take it further and modify how people sleep. If the dreams are so good, people don't want to leave. So they take pills to sleep longer, deeper. This changes their brain chemistry and how the machine responds. Dreams turn into nightmares, nightmares indistinguishable from real life. A nightmare they'll be unable to wake up from.
The addiction also ought to reflect on the user's appearance. It ought to be the more they use it, the more like shit they look. It makes sense, since they're perfect in their dreams and they sleep more than they brush their teeth, shower, etc. This goes against the horny of course, so I suspect that's the reason why the story doesn't go that route.
TL;DR - Interesting premise fails to deliver because of horny, pacing issues because of horny, and an MC that's hard to root for.