Sorry for the double comment, I ended up reading this one through the official channels.
I can see why it was cancelled/ended early as a promo. It had a ton of potential at the beginning and moving through the dungeon, but it started floundering when Titto (the thief class) was added. For some reason, it felt like it almost switched writers at that time because of the drop in story quality and momentum. The boss fight took a LONG time and there were many stupid mistakes(?) that happened throughout the fight. It also became almost overly technical in a few explanations, with the mangaka dedicating almost entire whole pages to just text.
The art quality is gorgeous, the characters are fun if not a bit generic, and I would have loved to see them progress as an official party in adventures, similar to how the Frieren manga approaches things. But alas, it is already completed.