While I do love and enjoy sci-fi novels, I have rarely come about any that involve Aliens. I can actually only recall 2: I Am Number Four, and Obsidian. Both were good and a great change from the same old. In Gravity, we get another unique addition into the genre. The world Melissa has created has some holes and grey areas, but overall, the mix of dystopian and aliens is a great way to create an original post-apocalyptic world with very neat, but also very scary, aspects. We begin this book with a prologue that occurs during Ari's childhood, when she has to face for the first time the very real fact that aliens are among them now, and what it means to live in this world with them. This chapter sets a great intriguing tone for the book. Making it instantly exciting, while heightening our curiosity of the journey we're about to embark upon. Then when we meet Ari again as a teenager, it's during a very stressful evening where, immediately, secrets are unraveling. We are off to a great start! Like I said, there are some grey areas in the world building when it comes to learning about these aliens. The Ancients are a fascinating bunch, although they have some key differences--like changing eye color and flawless beauty--they look like humans and have a neat way of traveling to our planet. We also get some greatly interesting biological detail. What we don't get that I wish we had is a lot more about the history of these aliens coming to earth. I'm not saying we don't get any information, we do, but I wanted more than the basics. When I think of a post-war world like this, I like to be able to imagine its history unfolding, and this was more like a hop. Bits and pieces that give a passable explanation, but not enough to really throw me into this world convincingly. Nevertheless, the idea for the world is both alarming and exciting, and I loved it. We are in the brink of a war with these beings. Things start to get tense when the first attack is seen early on in the book, and it keeps a great steady pace throughout. I did, however, feel a little underwhelmed with the romance that develops from the very beginning. I understand that it's an unusual situation since Jackson has been developing feelings for Ari his whole life, but from her side, she's only just met him, yet she trusts him immediately. This, to me, seems like a way to try to play in insta-love without ramifications. Although mild in this case, there will never be a "good way" to play in insta-love. It lacks connection and chemistry, and without these key elements I never feel very interested in the love story--which does come to the forefront for a big part of the book. What kept me rolling through despite not liking the romance is Ari herself. I loved her narration, especially that it's in first person. She is a character who is brave and independent; she's tough as nails and her training has made her a true fighter. I love nothing better than a strong female protagonist who can hold her own. With that said, my issues do lay mostly with the romance. It's a rather large part of the book so no matter how much I loved the plot--which was a lot--I couldn't get truly wrapped up in it as the romance kept getting in the way of my enjoyment. If I would have rated this on everything BUT, it would have gotten a solid 4!--An advance copy was provided by the publisher for review.For more of my reviews, visit my blog at Xpresso Reads