If the stress at the joints can be handled, they could be useful. Here is a
video of them taking off and flying, and
here is a ~10 minute video showing them flying an Ornithopter (and meeting the local wildlife).
They would have VTOL movement when the wings are moving, and fixed-wing movement when the wings are stationary. Switching from one mode to another is a minor effort, instead of the transformation needed by Land-Air-Mechs.
Moving around them when they are taking off is slightly safer, as instead of the round danger zone imposed by a helicopter's rotor, you only have the lateral regions where the wings are flapping up and down (though the wind currents will be nasty).
Potential Quirks:
Compact (their wings fold up so you can put two of them in a Vehicle Bay, if their total tonnage is equal or less than what the bay can handle)
VTOL (the wings are like a dragonfly)
Fixed-Wing (for straight flight)
Maintenance hog (keeping those joints lubricated and making sure there are no cracks)