When I first saw this book, I was pretty excited. I absolutely adore the Lux series (well, Onyx was just okay but the other two were amazing), so to see a full size novel set in the same world but focusing on other characters was awesome. It was interesting that the author chose to make it adult, considering the series it's based off of is YA. Personally, I didn't mind, but at the same time I wonder if a good chuck of Lux fans might shy away from Obsession for this reason. Hopefully that won't be the case, because this book has a lot to offer all on its own. It's not often that I get into novels focusing on aliens - sci-fi has never been a favorite genre of mine - but Armentrout makes it impossible not to get attached to everything about her works. 
 Throughout the book, it felt a little strange getting to know Hunter and liking him, since in the Lux series the Arum are always portrayed as the bad guys. In Obsession, the opposite is true - the Luxen are the bad ones, and honestly I can see why. There is something mentioned towards the beginning called Project Eagle, and as the novel progresses you learn more about it, and I'm wondering now how it will play into the main series, because there's no way something like that won't have an affect on the characters in the upcoming fourth book, Origin. Thankfully, it doesn't seem like I ever have to wait that long, because Jennifer L. Armentrout is some kind of mean writing machine - it seems like she always has something coming out. And she writes so much diverse stuff - contemporary to science fiction. She is truly a gifted author. 
 Serena is different from Katy. For one thing, she's an adult. But there was that same love-bickering present between her and Hunter as there was with Daemon and Katy. Both couples argue a lot, but it's a happy kind of argue, if that makes any sense at all. Hunter is definitely one of those bad boy exterior characters who actually has a good heart buried somewhere deep inside - and I happen to be a sucker for that kind of thing, so by the end of Obsession I loved, loved, loved him. The side characters - Lore, Dex, and a few others - were all pretty good additions to the story. You'll be happy to know that Daemon makes the tiniest of cameo appearances here - he doesn't even say anything, Serena just describes him a little (as being completely hot, of course). I greatly appreciated the lack of insta-love in this novel. Though I guess Serena and Hunter didn't know each other for that long, their relationship progressed believably. 
 Towards the end, my Nook glitched and I couldn't read the last few chapters. Finally it started working again the next day, but I was beyond annoyed I didn't get to finish the book then - the climax at the end is very engrossing. All of Armentrout's books I have found to be paced very well, actually. Her books are just fun, all around. Obsession is a standalone book, but I wouldn't be opposed to another Serena/Hunter story. At least let them make an appearance later on in the Lux series, please, Ms. Armentrout? 
 4 stars