So this is a combined review because I read these two in such quick succession. I'll try not to give away many spoilers however - seeing as it is the last 2/3 of a trilogy and it was awesome... well, I'll try. No guarantees thou.
A refresher - these books are volumes 2 and 3 of The Strain trilogy by Guillermo Del Toro and Chuck Hogan. It is a modern day vampire/horror story.
Let's start with vol 2 - The Fall (as I deem this the most logical course). This is my favorite out of the three. There's less of a OMG-are-those-vampires? and more of a OMG-vampires-how-do-we-kill-them? attitude. The characters are also really well developed at this stage so you can easily see which ones you'll like and which ones you won't by the time the series ends.
And although there's a lot of character and plot development, my FAVORITE PART OF THIS ENTIRE SERIES is the mythology that was developed. As mentioned in the end of vol 1. The Strain there is a book of great importance to both the humans and Ancient vampires call The Lumen (literally: the light) in which there's a detailed history of the creation of the vampire species and possibly a key to how they can be defeated. Much of the book is spent trying to achieve The Lumen either through duplicity, alliances or strength of arms. The mythology within The Lumen is what makes this story amazing... arg! I really want to share all of this with you but I don't want to give you spoilers! GO READ IT and then we can talk about it!
Another thing I like about The Fall is the non-traditional hero arc for almost all the characters. Well, on some accounts it's very traditional - mainly in the death department (I'll let you discover who and how for yourself.) But the journey of self-discovery that has to be made is a little different from most other characters in fiction primarily due to the huge role religion ends up playing through the last two books. It's not a preachy book but more of a spiritual and physical importance in the series.
Anyways, book 2 The Fall ends excellently, with the Master (and evil) pulling ahead of Eph (and good). Book 3, The Night Eternal, begins 2 years after the events of The Fall. Eph is rather estranged from his companions through his self medication (*SPOILERS* to blunt the absence of his son who gets kidnapped by the Master at the end of book 2 *END SPOILERS*) and alcoholism. Fet and Nora have grown closer but have yet to really move any closer physically due to Fet and Nora's guilt over "betraying" Eph for each other.
I really can't tell you much about The Night Eternal without giving away major spoilers.... so I guess the second half of this review is kinda bust. I will say that I go back and forth between liking and really disliking the ending. On one hand I understand why they did it, on the other I think it's a total cop-out.
I give Guillermo del Toro and Chuck Hogan's The Strain Trilogy (on the whole) 4 out of 5 stars for an excellent interpretation of vampires. Now - go read it so I can talk to you about it!