This series was pretty interesting, but I have a massive criticism; the names. The dang issues with the names were catastrophic enough for me to abandon the series (after book 2) all together. I really had to apply context clues to know what was going on, and even then, didn't often know until I could apply some retrospection.
I wish I had some specific examples but I honestly can't remember even the basic, main characters. Magda-on and Makda-on? And then Dagdon-ock? Kagdon-ah? Stuff like that. They were THAT similar. All of them. All of them.
Listen. I get that inventing a super neat native-y language was cool, but good god man, I couldn't tell one character from another character, or another character from a town, or a town from another town, or another town from another character. If you can't remember a character's name because it sounds like every other name in the book, then you can't connect with said character. If you can't connect with said character, then you typically don't care what happens to them. This was the case with me. I kept reading for a while not because I cared about what happened to any of the towns or characters (minus Alex, of course), but because I had nothing else to read.
I really wanted to enjoy these books because the concept was pretty interesting, but the weird invented language with the weird invented names that were all variations of like five different guttural sounds was just too much. I don't know how even the author managed to keep track.
Lastly, just a small pick, the writing suffered from a lot of redundancy, which is more a problem with the editor (if there was one) than the author. But lines like, "He moved silently through the foliage, trying to be silent," always grate on me. The double use of the word "silent" isn't necessary; use a similar word, or find a new way to write the sentence. "He moved carefully through the foliage, trying to be silent." See how much more sense that makes? It didn't happen terribly often, but was definitely common enough that it sticks out to me as a staple of the series.
Anyway. Not a bad one-time read, but I'm not sure I'd recommend it simply because of the impossibility of the crazy names.