Where's the spark, Perry?

I read Through the Ever Night in Nov.2013 - less than 3 months ago. Either my memory's getting fuzzy or Ms. Rossi's storytelling's getting sluggish, but the final installment of the Under the Never Sky (UNS) series is not as exhilarating as I've expected. But first, let's go down the memory lane, shall we..
Aria succeeded in getting Col. Hess from Reverie Pod to team up with Sable, the ruthless Blood Lord of the Horns. Aria arrived back in Reverie to negotiate; but Hess had another plan, he left the Pod only with his best soldiers, abandoning Aria, his own son Soren, and the rest of the population, in chaos. Aria managed to persuade some of the Pod Dwellers to flee outside, by stealing one of the Hover aircrafts, and took them to Perry. Meanwhile, Perry's tribe, the Tides, was forced to go seek shelters in the caves because the Aether - a tornado-like force of nature that (supposedly) wreak havoc to Earth's polar magnets - is multiplying and happening at different places in the same time. Cinder, a boy who was born with a rare DNA to control the Aether, was kidnapped by Sable; Cinder's the last hope of mankind (Hess' & Sable's groups) to lead them to the Still Blue, the land on the other side of the rainbow, err.. I meant Aether. Roar, our favorite supporting lead, has just lost the love of his life, Liv. He went back to the Tides but was ordered to find Cinder.
(show spoiler)
That's what I love about the book. With all the romance going on, there's still enough space for friendship. In fact, I appreciate how Aria can easily banter with Roar, and Soren not long after, without us readers imagining otherwise. Ms.Rossi succeeded in putting a heroine, though sometimes we wonder how Aria sniffs and cries a lot.. if it's due to female predisposition, then I beg to differ.
First, it's been 6 months (as it's often mentioned) since they met, and after all the struggles and adventures Aria had to face in that stretch of time, she still acts too girly, IMHO. Perry, on the other hand, acts like a gentleman, but since he has 'rendered' himself to Aria, readers have to endure his desperate longing for her
- it's like they have to mate every 5 seconds, even if it's only in his mind.. Still, it's quite entertaining; seems like the author has better knack in describing a love scene than action scene.
Now let's talk about action. Hoooo-hum! I don't mean it has as much action as Twilight (nonexistent ;P) but with that many guys running around one would expect a lot more. These are teenagers, for goodness sake. They're starting a revolution, and a new civilization. I'm still looking for at least one female writer who can write like Kathryn Bigelow does Zero Dark Thirty. Perry and Roar are warriors, so give them their dues and put them in kick-ass action sequences. Related to action, my biggest peeve is the Still Blue and how they manage to cross it (and how Perry survived it.) Should I imagine it like a Black Hole? Can Ms.Rossi give me a more believable explanation?
It's hard for me to give this a 3-star rating, as I've come to love the characters. The world-building is quite a feat, but after the second installment I'd like to see more scientific explanation of the Still Blue. Is there a way to convince YA writers to write like an adult instead of teenagers? And by that I meant less SAT words, but a lot more vocabulary to describe the world setting, for once. ESPECIALLY when these teenagers have to face some grown-ups. It's wishful thinking that these young people who are still in their teens can command respect and deceive wiser grown-ups, especially with the likes of Hess and Sable. Still, rationality can be off the chart in YA universe (hence the new term 'speculative fiction' instead of 'sci-fi' for 'grown-up' books..)
Last but not least, I hate the cover! Perry and Aria are far edgier than pictured on the book cover. Especially Perry: hell, no! He's like a muscled Edward Cullen played by Robert Pattinson. Please pretty please, get the movie version right (like Katniss and Peeta of The Hunger Games instead of Twilight's Pattinson and Kristen Stewart.)
For fans of UNS - this book will be a neat conclusion of Aria+Perry's adventure, but by the time you come to the end, Perry has lost the spark and become just a sidekick of the real star: Aria and Roar. I like the last chapter BTW, it makes you wonder what will happen in the Still Blue yonder :) I'm just saying, I want another BETTER sequel after this trilogy!