I didn't enjoyed Iron Flame. 
At least not as much as I thought I would.
The dragons are still the best part. Teenage grumpy Andarna was hilarious and Tairn is still my favorite. I would have wanted to see more from their perspective, because, to me, they're the most interesting and engaging characters of the series so far. 
The rest... 
I don't know how the publishing process was for this book, but it feels a bit... Rushed. Like it was written (and edited) in a race against the clock? Let me know if you get the same vibe. 
The pace was irregular, the dialogues sometimes felt  repetitive. And well, I've already mentioned how I feel about miscommunication. 
The plot twists were a tad predictable from all the spoon fed clues. And there are certain choices made for certain characters I certainly didn't liked. 
Can't say much more without falling into spoiler territory
So, to wrap up, it was a disappointing reading experience. Do I think the book is bad? Not a all. Am I going to keep reading the series? Probably, not sure. Most likely I'll wait until there are a couple more books to decide that.