Okay, first of all let's talk about writing quality, grammar, structure and things like that are pretty good overall, I believe that anyone in the seventh or eighth grade can read this, although there is room for improvement.
The story is developing in a pretty weird slow manner, some chapters doesn't even seen to make the story progress to tell the truth, this needs to change or improve since there is too many irrelevant information being written.
As for character design it's ok I guess, he is like me, you or any other common boy you could think of, however It looks like his time inside the world didn't changed his character at all, which doesn't makes too much sense for me, considering his new background he should have at least gotten a little bit more serious I believe.
Update stability, all I can say is that if the author didn't write so many irrelevant information in some chapters it would be a 5 stars for it instead of a 4, the way things are currently it would be better if he could publish one more chapter per day.
As for the world, I think its being well developed for now, but its too early to say anything, let's see if the author will continue to explain aspects of the world and show them happening instead of simply telling us readers about it.
Conclusion: 4/5 this is an above average fanfic, the main character is interesting, his powers are developing well and he doesn't feels like a broken character (YET), his relationship with the other characters need a little bit more of development since in 15 chapters it looked like he forgot his childhood friend which is weird for me, and there's even the fact that his parents aren't that present in the story. The canon characters seems to be well represented and they are what you would expect, which is good, since the author didn't changed their identity for a stupid reason like some fics do such as the Harry Potter ones that makes Dumbledore the villain, I'm completely hook by the possiblities of this story and I hope the author won't do a Harem, but in case its inevitable, please author remember to limit it to 2/3 girls, or boys, idk, your story, aheeem..., too many girls ruins the story and please make the way their relationship develops be something credible, love is something that takes time to form and it can't be rushed. Also don't limit the main character, with his powers and abilities he could be anything, even the conqueror of the world, just do remember to make sure that his actions are in accordance to his dreams/objectives/motivations.
Good luck author, I don't know if you have, but if you don't, you should create a patron, your fic has the required potential.
