How reliable are they? any issues with them?

the ones I have had were fine weapons, at least the ones made by Walther.

I've got a Smith and Wesson PPK that runs smoothly and reliably. The beaver tail in the back makes all the difference in shooting it without getting bit. I did have an interarms PPK/S that jammed constantly and cut up my hand.

I got to shoot a friend's blue PPK/s a few weeks back.

1) crap magazines will disable the gun... get factory mags and/or new springs
2) The type of ammo makes a difference as well. Most modern JHP will feed fine, but for range ammo, stick with RN FMJ

It does not like Tula or Wolf ammo that well. We used UMC and PMC 95gr FMJ and didn't have any issues with factory mags.

It seems to shoot/feel a little "nicer" than a comparable Bersa... just my $.02

I have a couple made by Interarms.  I heard that the Smiths had issues but then some say they have good ones.  The ones I have shoot and shoot and I've had them about 25 years.

We have had my wife's Walther for about 4 months and it has been perfect.

I've the S&W PPK/S and it runs flawlessly. I stick with 90-100 grain FMJ round nose, which is what it was originally designed for. I've also polished the feed ramps. From all the negative posts I've read, most center around FTF which are usually cured by polishing the ramps. Some others, though to a lesser degree, is it's not liking HP's. I don't see using HPs in a .380 as I don't think there is power behind it to get a reliable expansion so I stick with the FMJ's for penetration. I prefer the S&B .380's when they are available.

That's most of the negative stuff I've read. You can go up to http://www.waltherforums.com/forum/ and go to the PP and TP series folder for more information. I've found over the years that the majority of posts are negative when discussing a particular firearm. It makes sense though because people are having an issue and are asking questions. Then, anyone with an issue weather new or from 30 years ago jumps in.

Take this for what it's worth, mine runs perfectly but I've polished the ramps a bit. I also use 90-100 grain FMJ. PPKs like to run a bit wet meaning don't wipe it completely bone dry before a range session. I like to use a moly-Teflon lube on the metal to metal parts. Keep it clean. A lot of build up will give you problems. I usually go only about 100 rounds in a session and then break it down for a good cleaning and lube. I can get all in the black at ten yards rapid fire first round off de-cock. I've tried limp wristing and other ways to get it to malfunction but it won't.

Hope this helps.

Mine runs fine now after multiple trips back to S&W......  Was a jam-o-matic for a while.

I have a post war PPK/S in .32 that runs and shoots great.  I love it.  My wife's first pistol was a NIB S&W/Walther abomination in .380 acp –– also a PPK/S, and that thing was junk.  Halfway through the first magazine the rear sight fell out of the dovetail and wouldn't go back in.  We returned it with less than 20 through it and never looked back.  That post war pistol though is excellence.

I have an Interarms PPK that I bought around 1990 and it is great.
 

I just purchased a S&W produced PPK in 7.65mm. I took it out last weekend and put 100 rounds downrange with ZERO malfunctions or issues of any kind. I checked the serial # before I shot it (some are subject to recall for safety reasons). Mine was made in October 2011. The original owner never shot it. My only complaint is the cheap-ass plastic grips. They don't fit well and look out of place on an otherwise well made gun, particularly on the stainless steel models. I found a beautiful aftermarket set made for the S&W produced guns. They look awesome and really brought out the classic elegance of the PPK. I like mine a lot! However, my Wife is now sick of me walking around the house doing my bad 007 imitations

ETA-


and for those of you who don't consider the S&W made guns to be a "real" PPK, all I can say is;

That's funny.  S&B rounds were the only manufacturer that my PPK didn't like.  I got constant failures to fire and had to restrike rounds multiple times.  Winchester White Box, Federal, and Speer Lawman all ran like a champ though.  Seeing as the .380 is a bit underpowered as is, I've never bothered running hollowpoints.