I am going to make a slight criticism here, and I hope it's taken in the spirit intended. I really enjoyed Act 1. Yes, the game play is functionally "watch these progress bars fill up 400 times to unlock the next step of the game" repeated ad infinitum, but you really got the sense that the tasks you were doing were part of an overarching story. In large part this was because while doing these tasks, you would organically get interactions with persistent characters and each setting had its own semi-distinct flavor which was strongly tied to the elemental cycle underpinning the story.
I'm not getting that sense in Act 2 as much. Yes, there are persistent characters in Stonehold and Common Ground -- but you don't really interact with the ones in Common Ground so much as just hit their button 3x to clear them, and the tasks feel like rote check-boxes.
And in the Grave Engine tyrant area, at least, there *are* no persistent characters. Each location is just "fill these 4 progress bars with slightly different flavor text once each, fill this progress bar 5x, here's a progress bar that gives logarithmic improvement to these numbers for however long you want to fill it", with exactly one 1-paragraph blurb of text at the end of each location showing what you've learned. Yes, each location has some text describing what is going on, but it just not as satisfying as Act 1.
Maybe that changes as you unlock more tyrants, I don't know, but at least at the stage of the game I'm at, the storyline feels thin.