The "isekai arc" was good. Some plots were over-simplified but still passable. The "returnee arc" could have been promising, especially if a "rekai recovery scenario" is added. But since the plot was terminated now, we'll never know.

The ending could have given a closure on the reincarnation tower story. Be it a transition to higher plane, an explanation on its origins, or being able to go deep in the cosmos. Some cool skills were acquired but didn't have a chance to be featured so it's a shame. Overall, the pacing could have been dragged a little, to give a chance for his teammates to have significant impact towards the end.

Why is there no proper introduction of transitory cultivation realms in chapters 900+? A bunch of 'divine realm levels' and 'qi refining realm levels' were thrown around without any adequate definitions for them.