You do not need to have read FEED for DEADLINE to make sense, but you will have a richer experience if you do. The following review will keep spoiler free.
If you liked FEED for the worldbuilding, you will love DEADLINE. If you liked FEED for the Mason sibs, they're back too, but not quite as they were in the first book.
I can say I found some of the storytelling predictable, but that's me and that is, again, because I read FEED four times, people, because of how nuanced, subtle and intricate Grant's storytelling is.
The lineup of team After The End Times has changed, due to the events of the first book. Now it's Shaun at the helm, going through the motions of doing the living thing, driving his team crazy and being a jerk to them as he makes futile efforts to process his emotions and keep an grip on his increasingly slippery sanity. The conspiracy uncovered in the first book comes, literally, to his doorstep in the person of a doctor he and Georgia met in the first book. The team begins to realize that the events on the Ryman campaign were just the tip of a truly frightening iceberg.
The book begins with the same type of bang the first one began with, and although it follows a formulaic path, the story itself is nothing of the kind. There are multiple nail-biters, moments that made me scream and where I found myself fighting a lump in my throat and tears in my eyes, and there are at least a few moments where I cheered, and simultaneously praised and cursed Grant's name as situations got worse and worse for our heroes.
Shaun's need for info and desire for revenge play constant tug of war with his sanity, emotions, and the patience of everyone he's dealing with. The villains are villainous but also human enough that you can see their motivations clearly enough to understand them. The same is true with the heroes and those who help them. They're not just cardboard cutouts, but individuals that a reader will become invested in and care about.
There are new characters to love, hate, and love to hate. Same warning applies with every book by this author. Once you hit the 2/3 point — the book is going to become pretty much unputdownable. Make sure you've got uninterrupted reading time and enough sleep to make it all the way to the ending which will make you blink hard before you put the book down.
Five out of five.