I'm giving this 3 stars generously. Iron Flame needed at least 6 more months of editing and cleaning. Considering the extremely tight deadline, I commend the author and editors for their work, however I think we would've all benefited from more cohesiveness and comprehensiveness. The pacing was all over the place. Violet felt like an unreliable narrator at times. I think I need a reread (or three) to process whatever character development was attempted for both the main, and side characters. But the biggest and most outrageous issue I have with this, is by far the plot. Making use of popular tropes is one thing, but my first thought upon finishing this is that it's a poor copy-paste of a storyline from a popular series from a decade ago (choosing not to leave the name here to avoid giving spoilers). It's done in such a way that it could be forgiven, if it were any other series, but The Empyrian is such a phenomenon, that blatantly copying storylines from other popular series is just outrageous. I don't know if the author knows she did it, or is completely unaware, but an unprofessional mistake has been done on some level, and either no one cared that storylines have been copied, or they considered it negligible. A series with such a following as The Empyrian should not boast lazy writing and second hand plotlines. It is in no way negligible and I hope the writer takes note of this for future installments.
All that being said, it was still a somewhat enjoyable read. I'm giving it 3 stars for three things only: Tairn, Rhiannon and the fact that they didn't force us to wait longer for this. If they actually published this same book just a year later, I think the riots would've been entirely justified. At least we got this mess quickly and didn't wait for over a year for such a letdown. Though I do hope that the next one takes its time and uses said time to actually be a worthy book in the series.
Verdict: read at your own risk.