It takes 0 risks, to the point of being boring. In no way is this Seinen. I dropped this after the MC literally said "I don't want to have sex until we return to my world".
The characters are cardboard cutouts. You have an MC who is the chosen hero, invincible in combat despite never being trained, who wins every fight save 1, never suffers more than bruises, and passes out after every fight from magic exhaustion, who won't sleep with girls unless the "timing is right", even if they offer to have sex with him. Even if they offer to have sex with him... 4 times. You have the childhood friend who goes from "I don't want our relationship to get in the way of our friendship" to "I don't want you to pay attention to other girls". You have the timid girl, who has no traits other than timidity. You have the flirtatious feisty girl. She got a whole two traits to her! I dropped after the third heroine. All other side characters were generic and frankly unimportant, both to the plot and the dialogue. 3/10 characters; I don't hate them, but I genuinely don't care about or relate to them at all.
On to the plot: Bad. Generic fantasy transmigration, but with no worldbuilding. Evil is attacking. Why? Because it's evil. How do you beat the evil? Only the hero can do it, and he has to rescue the princesses to do so. How does the hero beat the evil? He... slashes it. Occasionally after having his sword repelled the first time. Do characters die? Ha, what a joke. No, one character died in the whole time I was reading this, and it was an evil noble who we had been introduced to in literally that chapter. Even the intelligent, non-monster evil enemies all live, and it turns out they weren't evil, just mind controlled. Every location is generic. We go from a generic castle to a generic forest to a generic elven city to a generic arabian city. Technically the last one on that list is supposed to move, but that had practically no relevance to the plot or setting. There are no discussed repercussions to actions. The MC abandons the castle, with no thought given to anyone there. He breaks down the elven wind shield, with no thought to how they defend themselves now. There is no transition time; you leave one place, and you get to the next almost immediately. 2/10 plot.
And now for the ecchi, one of the main selling points! It feels like every chapter has about 25-50% of it devoted to ecchi. That said... we're talking the crappy filler episode kind of ecchi, where nothing is shown, no one does anything, and the raciest we get is people sleeping together naked with no action. And I mean "no action". The MC doesn't even touch the girls, they just cling to him naked and he acts like the block of wood that he is. It's terrible. 1/10 ecchi.
Art. Could be worse. I mean, it's fairly well drawn. I'll give it a 5/10 for being consistent, but it can't get higher because of how utterly crap fights were; you rarely see swords collide, let alone any actual martial arts.
Enjoyment: God this is generic to a fault. That said, if you are every really bored and want to read a generic harem... don't read this. A bored person reading this might die of boredom. Go back and reread some other shounen ecchi harem. I guarantee you'll get more enjoyment out of rereading something you already know; the plot was so generic that I felt like I was rereading this even though I'd never even heard of it before. 1/10.
Overall: 2/10. Takes no risks, and sucks for it. Even on the scale of generic shounen novels this is boring. I normally rate on the high end of the spectrum (6/10 is usually the limit for "doing nothing wrong"), but this is so risk-free that, despite doing nothing wrong, I actively ended up dropping it with more of a feeling of dislike than I feel for genuinely bad mangas. This is probably one of my two lowest ratings of all time. I only wasted 3 hours of time reading it, and I still want a refund on the time I spent on it. I'd rather read something crappy than something so generic that it couldn't be crappy if it tried.