I have both the Mosquito and the P22. Both have been continuously bad mouthed on most of the forums, (often by the same person, over and over, and often by people who dont even, nor ever have, owned one) but both of mine have been flawless since day one, and both are early guns. A few of my buddies also have one or the other or both. We must have got all the good ones, if you listen to the way people complain about them. The gun shop where I bought mine has sold a bunch and hasnt had any come backs, none that they will talk about anyway.
Both guns do recommend higher power .22's, but mine work fine with plain old HV's. Both guns do come with two springs, to compensate for different power ammo. Both of mine are still using the spring that was installed when I bought them. I often wonder if people ever read the manuals and/or tried the other spring before they gave up on the gun.
Both guns are fun little pistols to shoot. They are not target pistols, but they are plenty accurate enough for most everything else.
Over the years, I've owned at least one of just about every .22 autoloader maker out there. Rugers, High Standard, S&W, Colt, Browning, Beretta, etc, so I do have something to compare them to. The two I have and shoot right now are the Mosquito and P22.
One thing for sure with all of them is, they all are ammo sensitive to some extent, be it accuracy, function, or both. If you dont clean your guns every time you shoot, your going to have problems. This can often be just after a few boxes with some, others (not many) will go more than a brick. 2-300 seems to be about when I usually start to encounter troubles.