I've read the original novel All You Need Is Kill over a year ago, so I don't remember all of the finer details that did or didn't make it into the manga. I will say though, all of the important stuff is there and this is practically a perfect adaptation. Personally, I enjoyed it more than the novel (you should still give the original novel by Hiroshi Sakurazaka a shot, though!). The story and characters were still there. I enjoyed them just as much - probably even more - than the first time around. 
 Takeshi Obata's art style and characters designs look amazing as always. The emotion he draws on the characters' faces pulls me in every time. Their look of sadness, happiness, and anger just looks so believable. I'm so glad he did the artwork for this manga. I loved Rita's design, especially! 
 This manga is a standalone combining both volumes that were originally released separately in Japan. Whether you're knew to manga and want to get a whole story without having to buy 10-20 volumes, this is a good one to start with. Hell, if you're already a manga fan this is a great one to add to your collection.