I have had the opportunity to fire a number of PPKs over the years. With the post-1968 ones sold by Interarms and S&W, I think it's a crapshoot whether or not you'll get a good one. I have seen ones from both Interarms and S&W that wouldn't reliably feed even ball ammo, nevermind FMJ. Needless to say, these were NOT guns on which you would want to bet your life, which is precisely what you would be doing if you carried them for self defense. If you have an Interarms or S&W PPK, and it works 100% with your ammo of choice... great. Carry it with confidence and worry no more. But if I were looking for one to buy, I'd be a little antsy, knowing the odds of getting an unreliable one.
I personally would rather have one of the pre-68 Walthers. You'd possibly have to send it to a gunsmith to have it throated before it would feed hollowpoints, but I've seen some that would feed JHP reliably, and I've never seen a German made PPK that wouldn't feed ball, the way the license-built, U.S.-made ones sometimes won't do. I've also never seen a German-made one that didn't have at least a decent trigger.
Interestingly, my department recently confiscated a WWII, Nazi-marked PPK, in 7.65mm (.32ACP) from a guy arrested on drug charges. It was a rough, late war production gun, with, plain, uncheckered wooden grips, a spotty finish and visible tool marks, and yet it still had a vastly better trigger than the brand new, stainless steel, S&W-made PPK on the shelf at Bob's Gun Shop in downtown Norfolk, which I looked at the next day. It broke my heart to know that that old war trophy was headed for the chopper.