HOW I LIVE NOW is a poignant, disturbing, enthralling, and horrific film. Wonderful soundtrack and natural imagery that contrasts beautifully with the ugly and treacherous human world. Allegorical qualities: We don't know many of the specifics of who the terrorists are, the backgrounds of many characters, their full names, exact locations in Britain, etc. In those and many other respects, HILN is more for the heart than the head.
Good performance by Saoirse Ronan as Daisy, a brash, cantankerous, and troubled American teenager who is sent to live with some distant relatives in the English countryside. Ditto for the others who play the various teenagers and children. However, the relationship between Daisy and Eddie develops a bit suddenly and unconvincingly; with everything else that is happening here, the character development suffers. I have not yet read Meg Rosoff's original novel, but I would guess that it is yet another book that can never be done justice on screen. Nevertheless, I found this film well worth watching, and it should prove especially useful as a basic illuminator for the book.