First, I agree with everyone that the first Marco book is pretty great. Honestly, any book with Marco as the narrator is pretty great IMO. Off-hand, I can't think of any of his books that I didn't like, and with every other character, there was at least one of their that I did not enjoy (some more than others, without naming names). I like the fact that Marco can think through things to see the necessity of certain actions to reach a desired outcome (end justify the means). It may be ruthless at times, but in a war, that's what you have to be sometimes. (I'm probably getting ahead of myself here, though, as much of this is developed in the future.)
Regarding this book in particular, the plot twist definitely makes the book, and there is plenty of interesting action before that, but I gotta say that I hated the initial premise of the book. Especially looking back after having read the whole series, I realize I did not have a great impression of Ax early on. I like his character later, but early on, he definitely shows his arrogance and naiveté in regard to military matters and just generally how to behave in a war. Later on, we can see his character development and improvement when we get to see him contrasted with other Andalites as in #18 or #38.
In addition to his arrogance (he constantly belittles humans and their technology, etc. starting with this book and continuing on for a few dozen), despite not having fought in a single battle (exclusing the Taxxon "battle"), the following actions by Ax really make me think very little of him as a first impression:
- First, the whole book is about Ax wanting to get home because he's homesick. This puts the other Animorphs, their entire mission, and the future of the human race in general in jeopardy. (I think if Visser One was really aware of who they were, she probably wouldn't have taken the actions she did.) This is entirely selfish and cowardly on his part. He talks about the importance of honor and wanting to fight against the Yeerks, but then he wants to run away as soon as he can. I understand that this was the plot that was needed for KAA to divulge Visser One as Marco's mother, but still...it makes Ax look like a pretty weak ally early on.
- Second, twice Ax runs off in the mall when they are trying to get supplies for the device he wants to build. Even if you want to attribute this somehow to the "instincts" of the morph, I can't imagine it should have been that difficult to control. He knew they were on a strict time schedule for morphing; he knew they were doing this for him. Yet, he completely loses focus of their mission and runs off like the child he apparently is. I would expect more out of the Andalite aristh training.
- Thirdly, when Ax is being chased at the end, he begins MORPHING into his Andalite form right in front of everyone. By now, he should understand the importance of secrecy in public with the Animorphs. This could very easily have caused all three of them to get caught and killed/infested. But, even the simple exposure here puts the Animorphs and their mission at risk. I understand that Ax was frightened because he was being chased and perhaps defaulted to his "battle form", but still, he should have been smarter than this if he is supposedly so much smarter than the humans. This is just a general result of his prior negligence as well.
Another thing in this book is that when they all turn into ants and are nearly killed, Marco has nightmares. This is understandable, but this experience freaked out everyone (and probably gave them all nightmares). Marco even mentions that everyone is freaked out afterwards. My problem with this is that in later books, Cassie and others (but especially Cassie) try to pin this all on Marco, that this experience only shook him and him alone. This is probably due to the fact that Jake nearly gets swatted to death as a fly in book #16,
but it just makes me annoyed because it is a poor account of what happened, and it never gets corrected.