3.5 stars
I definitely enjoyed THE FOURTH SPECIES more than THE HIDDEN BASE as it feels like more happens, that the world is changing more due to the events of the book. I would say that it's not really the characters' actions but the villains who are doing the changing.
I think, drilling into it, that this is the reason why neither the second nor third book have grabbed me as much as the first did. The POVs' actions aren't the ones driving the plot - they're reacting to the world around them, or doing (in some ways) unnecessary (to the overall plot) tasks designed to get them in places where they can find out information. This does give a more passive feel to the story overall. That can work for some stories that are much more character focused, but this is a series sold as a more action-based one. This said, it was a more engaging book because it did feel like more was happening, that the characters were facing bigger stakes and threats.
There's a new POV introduced in this book, the third one of the series, Genevieve. The information about her is tightly controlled in the book, with all the reveals coming later. However, not getting those reveals early on left a bit of a gap, I felt, because the character presented didn't have any reasons to make them one you wanted to invest in, wanted to like.
She was very focused and robotic without those reveals. There wasn't really enough time after the reveals (as it's such a short book and the final one is her final chapter) to really get to know her/soften to her.
The ending very much has the feel of "penultimate book, so all change please." I'm not sure how many books there are, but I have quartet in my head for some reason, and this book only reinforces that for me. Compared to the size of the book, the denouement is rather long (about a tenth!) as it sets up the next book, which did add to the feeling of this being another book about getting things in place.
I am going to finish the series, and I hope it manages to live up the first book, which is my favourite so far.