So...Vivid Strike.
I feared you would be a boring, derivative spinoff of Nanoha Vivid. Just training montages and so-so fights without the vicious bombardment of a proper Nanoha title.
But, I'm honestly engaged with the story they've got going between the newly introduced duo. It's very much the same kind of thing we'd expect out of a Nanoha-type series, and it's certainly not revolutionary, but the way they've developed it is...surprisingly good.
It has elements that long-time Nanoha fans will instantly recognize, as Fuuka and Rinne's story has strong similarities to Nanoha/Fate or Subaru/Ginga, but there's something else going on. It more closely follows Nanoha's original story, Triangle Heart. Fuuka and Rinne are more rooted in realistic origins: they're not some mystical reincarnation of ancient heroes, cyborgs, or clones. They're troubled youths who went down two very different paths and became two very different people.
Proper shonen rivals, this is. Former friends, driven apart. One went to violence, one went to privilege. Both disgusted by their own weakness.
Obviously, if you're not into the Nanoha franchise, definitely don't even bother.
Major bonus: OP and ED are very good. Another good song by Minase Inori, who you'd never know from her VA work, is quite an excellent singer (unless you watched crap like I do, Symphogear 3 >_>).
Front Mission anime when?