This is the light novel version of the web novel by the same title; if you're hesitant on reading the LN, you should check out the reviews on the web novel version. That being said, this is one of the most enjoyable series I have had the pleasure of reading. There is consistent character development and worldbuilding, though it can get somewhat confusing. The main character is persistent on gaining stronger, though it serves as a means to an end and is not his ultimate goal. His growth in abilities may be a lot to take in at first as you try to chain together his abilities; there's no consistent reminder for readers. However, that's alright because the worldbuilding is the focus of the story and not gaining strength. Character-development wise, we know the main character and the side characters relatively well. They are well-developed, and despite the "Harem" tag the females actually have a decent amount of backstory instead of just female heroines thrown into an endless pit of women (for the most part). However. There's actually less romance than you might imagine because our main character is who he is. Other characters NOT a part of his harem are largely memorable because of the unique aspects of each character.

Action scenes are a bit hard for me to grade since I'm not an expert on how action scenes should be written, but you have a relatively clear idea of what's happening. Either way, you'll probably be reeling in just how overpowered the main character is. He still has his limits though, so it still makes for an actual struggle instead of a random power fantasy.

It's a great novel. Read it.