If I had to judge it, I'd say it's "so average, it's good".
Not a blockbuster, but fairly enjoyable.
Because...fanservice...*shifts uncomfortably*
There's been plenty of side-stories though. They actually have a Strike Witches Wiki nowadays. Keep tabs on all those sweet, sweet characters.
Ogitsune also regularly draws SW stuff, plus did a (still unfinished) SW doujin, the "Battle of Britannia".