There is only one thing 99,99% of the reviews and opinions on this series have in common: that this show's original score is Crowning Music Of Awesome and that their approach to the Post-Apocalytic genre is unique and it works. I assume that to be agreed upon. Everything else is anyone's two cents, and here are mine.
You can have a summary of the premise of the show on the page proper. The story then develops in a big, slow-paced arc and a small Grand Finale arc where a couple of plot threads come together with the previous arc. All the beginning story arc does is to set up the girls and their personality to justify the dangerous decision they take later. The show is all about its theme, the theme being "What does it take to keep on living on a Crapsack World?". The answer being, faith and family. Faith as the belief you can make a better world; family as your Nakama if it has been taken away from you, living for the sake of the people under you wing, and transmitting these values to them. Although religious faith is depicted a well-meaning, it is also presented as divisive: paraboles may become something to fight over, not enlightening teachings. Hope on the goodness of human nature is symbolized by Music, the Sound of the Sky, something that everyone can understand when words are an obstacle. This is the meat of the series, told over 10 episodes of Japanese girls in a Spanish town under Swiss rule doing the laundry, cooking, repairing an spider-tank, and fawning over glass dolphins.
If you're expecting a masterpiece, nope, not here. Animation is uneven, character design is derivative, drama and humour have the subtlety of an sledgehammer. But if you're expecting Military K-On!, you'll be out of the K-On! part pretty soon. If this show was an RPG character, it would be a Glass Cannon: it hits hard, but can't take much abuse. However, it mostly knows its limitations and avoids them really well. A cheap slideshow is turned into a Crowning Moment Of Heartwarming by skillful use of music, Scenery Porn and dialogue; a really awful animation of a Freak Out is followed by an awesome Mama Bear moment from my personal Ensemble Dark Horse of the series, Filicia. At the very least, this is an unusual war tale that is not afraid to go sappy and narmy when it feels like going there. Hey, sue me, I love Macross too.