Your mileage may vary. I find the writing crude but I still enjoy the books as light reading.

My main (but not only) beef is that the narration of the dungeon (the "ai") talks like a 16yo boy. Lots of swearing, sexual allusions, whores and bitches, etc. Then the main character rolls his eyes or makes a comment to show disapproval. But it's still in the book, constantly, so you're supposed to find it funny.

No plot holes as far as I can tell, though.