Eric Vall's Summoner is, quite honestly, a typical Eric Vall book, to paraphrase a review I read before buying this audiobook, narrated by Joshua Story.
There's harems, power fantasies, magic, and every woman the MC meets is "the most beautiful woman I've met".
There's sex, action, and a typical "power that is typically seen as worthless is actually very powerful if used correctly/the MC has a way to make it stronger" kinda plot.
The MC is looked down upon, until he defeats one of the strongest students at school easily, and he's a cocky dude that every woman fall in love with (for whatever reason).
Now, if I haven't deterred you with all that, back to the review.
While everything I've said is true, the book was actually an enjoyable listen. The love interests are cute, and Vall at least try to make them larger than their tropes, unlike many harem animes he's definitely basing this book on.
In general, Eric Vall is a hit or miss kinda author. If you either have read Eric Vall before, or enjoy the magic high school harem trope from anime, then you'll most likely enjoy this. If you haven't read Vall's works or watch anime, then read through the first part of my review, if any of that puts you off, don't buy this book.
Overall, I'd like to give the book a 5/10, since it's not necessarily bad, but it's not great either.