This book is quite an achievement. Unfortunately there were a few elements that just didn't work for me. I did love the epic scale and worldbuilding. I found myself surprisingly curious about the Primaterre and what comes next for them. The writing doesn't have much unique style, but it flowed well. My brain enjoyed processing it smoothly. 

It's a long one. There were a few points where it slowed down too much and I got bored, but the plot picked up again soon enough. The mention of cosmic horror is what piqued my interest. There's a fair bit of buildup towards this aspect, it's a while before you see how it links to the characters. These being Commander Cassimer and his team of soldiers, who find themselves on a planet that seemingly hates them (Cato), faced with various difficulties to complete their mission and discover what happened to a generation ship. They meet Joy, a woman who escaped a different generation ship, and slowly induct her into the team. 

This universe and its various factions are fascinating. It's obvious there's something odd about the Primaterre and its 'demon' enemies, but you can also sense weirdness from the rebel organisation RebEarth and the inhabitants of Cato. So I was hoping for tighter worldbuilding as the book went on, but I could never figure out exactly what it was trying to say in the end. Iron Truth came off as more of an introductory adventure rather than the definitive start to a saga.

The main characters, Cassimer the hardened soldier and Joy the young woman out of time, are where this book lost me. Joy's unique experiences should mean she's an interesting person to follow, but her characterisation was so...silly. She's 23, but reads as much younger. Her decision-making is too immature and she's obsessed with her brother.
Cassimer's chapters were more engaging, especially the glimpses of lore and interactions with his team. But beyond his demon trauma, I couldn't see him as a fully fleshed out character. 

Once it became obvious where the story was headed, I didn't gel with the chemistry between Joy and Cassimer. I was hoping this book wouldn't have a romance plot. It didn't feel necessary, as the story already hooked me without it. Maybe it could have worked with different main characters, but the ones we got were cliché. 

Joy makes some incredibly dumb decisions. She gets led into killing a friend way too easily. I became put off by how her characterisation as a very young and naïve girl was matched with the grizzled older soldier of Cassimer. This romance was unappealing to me, so I found the plot development of Cassimer asking her to join his team very silly. She's not a soldier. These two are the heart of this book, but I wasn't keen at all. The obsessive aspect of their relationship fell flat. 

The book constantly reminds us of how physically weak she is too, the soldiers literally have to carry her around using their power armour. For a crack military outfit on a secret mission, it's very unbelievable why they make concessions for Joy. It's somewhat addressed later when Florey attempts a coup, but I couldn't buy why that was so easily dismissed. I couldn't believe the team would accept an untrained civilian as a private and ignore that Cassimer's judgement is clouded. The mystery around the 'demon' corruption is what kept me going in the end. 

And that last 10% was hard. It was all clichés and miraculous happy endings. It's weird that even Cassimer himself knows he's not fit to lead, but his superior insists on not accepting his resignation (because that would take the fun out of the next book). Also, no one comments on the fact they destroyed a planet despite the people that live there. Although they are non-citizens, they are still human.

The tone of this book is weird. The Primaterre is a fucked up empire and that's not explored enough. I'm not saying the first book in a series needs to cover everything, but I frequently found myself wondering if they're supposed to be the good guys somehow. The romance took centre stage, which is a real shame. The politics and mystery would have been better focus points.