I summarised this series before; but now at the conclusion I can say it was the hit of the new-in-Q3 titles.
All too often, anime series manage to lose the plot spending too much time setting up panty shots for reasons of fan-service, and not enough on the story. Strike Witches managed to avoid this common trap by leaving the girls half-dressed at best (though also including a number of steam obscured hot bath scenes for "uprating" in the DVD release).
By this ruse of continually running the fan-service in tandem with a setting that panders to the military otaku by including a wealth of period detail all over -- like making Sanya Litvyak's magical antennae (lower right) match those of the plane her prototype (Soviet ace Lydia Litvyak) flew; or naming Charlotte "Shirley" Yeager's plane after Chuck Yeager's Glamorous Glennis, to name but two -- Studio Gonzo have succeeded in making a series where the fan-service actually receded into the background. Once you've watched through the dogfighting in the first few minutes of the first episode, you get desensitised to the full screen pantsu.
The story is a fairly standard and slight one, but executed with style and humour, and just a little dash of "monster of the week" -- Yoshika Miyafuji is taken from the land of Fuso to Britannia partly in search of her father, but eventually to help protect against the scourge of the Neuroi, extradimensional invaders who have overrun much of mainland Europe. So there are friendships, rivalries, personal sorrows, and the inevitable brass who don't care for the unorthodox nature of the 501st Joint Fighter Wing, right up until the time in September 1944 when Gallia is liberated.
And then we end with a teaser for season two, which seems a given, the series having been an unexpected runaway hit (having apparently been pitched before last year's mecha musume title, Sky Girls, by the same designer, but left to later), an hit which may well have saved the studio financially.