It does as it intended to do, provide pure fanservice. Includes all (literally) the characters in some sort of fanservicey way. If you like the characters in this anime (no matter what gender) and you wanted to see more of them, then its for you.
Artwise, its the same as the parent series. Nothing exceptional, but not lacking
Likewise, for sound, is also borrowed from the parent series. Explosions sound like explosions.
It really doesn't feel like an OVA, more like a series of shorts bundled together. Of course, the shorts have a coherent story in them.
All in all, I consider it better than the parent series
because it does what it needed to do and a little more.