Played this today.
I loved the use of maps and objectives. The missions never felt stale or repetitive. The tone was right. I actually loved the cavern map because the light effects on the Banished Pantheon villains helped draw you through the path. I particularly loved how the typical big chamber dead-end looked because you could just make out the chest lights of all the banished pantheon zombies, and that was wonderfully creepy. (Though the danger was diminished a bit by playing a beast mastermind, and my animals were able to easily manage it for me).
Two slight issues (one obviously not your fault).
Every time I entered a mission all my pets died. They didn't despawn--a bug that happens occasionally whenever I enter a door mission in the "regular game." They literally died and I walked in over a pile of dead wolves and lions that I had to resummon. This does not happen with the story arc I made, so I'm not entirely sure why this is happening in yours.
On the hospital map, there's a spot on the first floor that kind of contained by hospital room screens you have to jump over. Schism got trapped in here somehow and refused to jump over any of the screens and I had to just leave him behind. I didn't need him to beat the map, but I don't know if you've gotten any complaints about it.
One of the odd things about this story arc is how it feels almost out of time now that Dark Astoria has been changed to an end game zone. It's been a very, very long time since I've played COH, of course, but I vaguely remember doing the Banished Pantheon arcs when the game was young (I did every single leveling story arc on the hero side). But now I think some of that story has been pushed back to end game, and I really don't know what the Banished Pantheon are like now, and that makes the mission a little mysterious and confusing. It would probably be more impactful if we were playing around in Dark Astoria still in the original incarnation of it.