PA63 is a good workmanlike carry pistol with some nifty features.
For starters, its got a trigger activated firing pin safety which has two primary features: First, until the trigger is pulled, the rear of the firing pin is not lined up with the hammer, so a smack to the hammer cannot fire a chambered round. Second, until the trigger is pulled, the firing pin (safety on or off) the firing pin is unable to move forward. The firing pin also has a strong spring. Its drop safe, in that until the firing pin is raised to line up with the hammer, its mechanically blocked from moving forward. These are design features that are NOT present in the Walther PPK.
Mag feeding issues are rare EXCEPT with with the truncated cone shaped Wolf ammo, which hangs on the front of the mag. Mine has been uber reliable (its a .380 model).
Trigger pull "out of the box" is exactly what you would expect for a design based on the Walther double action trigger mechanism, which has the double aciton pawl at a serious mechanical disadvantage when pushing the hammer. Even so, polishing of the sear and D.A. hammer surface, as well as using a slightly less powerful hammer spring can bring very acceptable performance to the trigger.
The safety is indeed hard to turn on and off on a less worn pistol, which is a function of the detents in the safety lever. If you pull the lever out and dress the edges of the detent holes, it works a lot better; however, I should mention that I carry mine hammer down, round in the chamber, and safety off. The safety has a good decocker, and even with the safety "ON" it is possible to open the action or feed a round from the magazine. (if you do this, as soon as the slide closes, the safety will tripp the hammer drop: Don't worry, the safety blocks the hammer and if you don't have the trigger pulled the firing pin can't move forward anyway.
Most people replace the recoil spring with a slightly heavier version available at Makarov.com.
As a "fixed" barrel gun, the accuracy of these little guys is pretty good. I recommend against shooting the heaviest 9x18 loads or CORBON of any kind in these aluminum framed pistols, however -- especially if you leave the stock spring in it.
Sighs are lame: small notch rear and tiny front machined right into the frame. However, any good smith can mill in some dovetails to allow for a broader selection of sight options.
Like the original Walther PPK, the slide is "low" so there is a possibility for "snakebite" from the sharp bottom edges of the slide if you adopt a "high" hold. Also, as a relatively light pistol, the recoil is surprisingly abrupt, and some shooters complaint about that.
Parts are relatively scarce. The pistol's firing pin does not have a "forward travel" stop built in, and although of better metalurgy than the old Spanish Star pistols or the CZ52, the pins can break if the gun is dry fired without a snap cap. The firing pin is a complex one, and its not something a smith will be able to "fab" up for you cheaply, so always keep a snap cap in the gun.
The pistol, becuase of its size, had to have a thumbrest grip installed upon import to the US. There is a "slimline" plastic grip for sale on Makarov.com that is simply FANTASTIC in terms of the improvement it makes. (indeed, most "high holds" that result in snakebite are a result of the poorly placed thumbrest on the grips most of these pistols have).
PA-63s should run between $140 and $200.
A shorter grip and barrel version called the SMC-380 usually goes for $250.
Commercial versions from Kassnar and Interarms can be located as the "PMK" and "PPH"
Incidentally, these are what you should click to on Numrich if you're looking for parts for your PA-63. It is NOT QUITE fully compatible with a Walther.