I enjoyed the first half of this series, but then they started going around doing concerts and... yeah. It's set in the Strike Witches universe (specifically, during the events of the first season), but it's an idol series. They don't fight. They're only ostensibly in the military. They don't go up against any Neuroi.
You could almost call it slice-of-life. It's tame and a bit on the pointless side. Also, there's no nudity on display this time.
Apart from that, though, it's okay. The cast are fine. Nothing particularly special and I don't imagine I'll remember who they all were in a month or two, but likeable enough. Almost all of them ended up in the Luminous Witches after being booted off combat roles for one reason or another. (Aira got injured. Maria has anaemia and can't fly properly. Gracie got too old. Milaasha can't shoot straight.) The show also makes significant use of the girls' familiars (magical animals that provide their powers), which I think is a first in this franchise.
The first half of the series is still putting the pieces together. "Useless" girls find each other and discover that they might have a role after all. Ginny hadn't known she was a witch in the first place, or even what a witch really is. They mess up their attempts at training. They try to hide their areas of incompetence in ways that damage their ability to do their new jobs.
But they also learn. All that is reasonably watchable.
After a while, though, they're just giving concerts. They visit North Africa, New York, Russia (here called the Orussian Empire), etc. I think every episode is a focus episode for at least one of the regulars, but that's not enough to save the show. It's still sort of okay, but you could probably skip the show's second half and not miss much. There's a bit of plot business circa ep.11, which the girls treat as practically a bereavement, but its resolution is unsurprising.
I wouldn't say "don't watch this". I don't dislike it. If you're doing a Strike Witches marathon, by all means include it. It's better than many idol shows... but it is still ultimately an idol show and thus basically pointless. I can see that singers could play an important role in improving morale, raising money for war funds, etc. but I still don't really care. It's tempting to offer a small prize to anyone who reaches the end of the series without having slept through any of its episodes.