The potential for this to be a really good science fiction novel exists. Unfortunately, it's just potential. In order to achieve that, it would need:
1. Another round of editing. A few tense shifts, some head hopping, and some grammar mistakes need to be shaken out. The beginning of the book could use a little work, especially keeping in mind the old writer's saying "show, don't tell".
2. The book needs to decide what it wants to be. Mostly, it looks like a coming of age science fiction adventure novel. But then, out of nowhere, two characters start quipping about man salad (in the context of eating...ewww!). This does not belong in a young adult novel. Then we suddenly get a bunch of romantic angst that feels quite out of place. This could be a good young adult coming of age adventure, a good science fiction comedy, or a good romantic hero story. But it can't be all three at once.
3. The setting needs more thought. It has futuristic technology. But it also has modern day things like Google, Snickers Bars, and new releases of modern video game series. It also apparently has events based on Roman history. A war is in progress, but who is fighting and why are never really covered. They're just generic rebels.

If those three things could be fixed, this would be at least 3 stars, probably 4. But alas, this e-book is already published.