I've owned my Solo for a few months now, and have about 1k through it.
Yes, they are very ammo sensitive. Mine has been 100% with good, defense ammo, and Winchester 124 grain NATO ammo. The NATO ammo actually chronos a little faster out of my Solo than +P ammo. Using economy ammo in a Solo is a crap shoot due to the tight tolerances designed around self defense ammo. I've played a little with handloads, but, haven't worked anything up that was hot enough to be reliable in my gun.
I've taken it apart several times for cleaning/inspection, and haven't seen any evidence of some of the problems that were reported on the early guns.
Recoil is pretty snappy, and for a defensive pistol, the trigger isn't too bad, if you don't mind a revolver-like trigger.
The reason I chose the Solo over other mini 9s, was that a Crimson Trace laser grip was available. All of my defensive pistols wear them.