I agree with what so many other readers have said: The lack of character progression is maddening. Thor, especially, just keeps forgetting he has special powers, even after all he's been through, and just makes the same mistakes over and over. How many times do we have to hear Godfrey's inner monologue about how he's not a hero, only to have him miraculously step up once again and save the day. Why does he never think, "Oh, I did that courageous and brave thing just last month, I can do this"?
Plot holes or just lack of any creativity is rampant (spoiler alert): The part about Ragon having Thor's son but not telling him, "saving" that news for the next day - are you kidding me?! That's just ridiculous! And then you want me to believe that someone as powerful as Ragon couldn't stop them from sailing away? Or couldn't even scribble a note on paper and have the dragon deliver it (or an owl, after all, he's a wizard:), or a pigeon)? No, let's just have the dragon circle a couple times over their heads and screech, I'm sure they'll get the message. It's not like they're sailing into mortal danger, or losing his son once again. Come on!
And don't even get me started on all the editing mistakes in this whole series. Spelling, grammar, even saying the wrong character name - on almost every single page there is an error. In every book in the series.
At this point, I'm only reading these to see where it all finally ends, hoping it does. finally. end.