1) The trigger bar is a very long, too thin, piece of metal with a bend in it. Consequently, it flexes when you pull the trigger making for a very long, mushy trigger. With time, it eventually becomes so flexible that the gun won't fire when you pull the trigger! Fortunately, this is actually a very simple fix, you simply beef up the trigger bar. In my case, a couple of additional pieces of metal epoxied to it have worked wonders.
2) The plastic stock will bind the magazine and cause failures to feed if you tighten the screws all of the way back up when you reassemble it after cleaning. The solution is simple, you don't torque the screws all the way down. I suspect this issue is what plagued it more than anything since it made the gun unreliable for anyone that didn't read the manual.
3) There are 2 small springs that come off and are easily lost when cleaning it. They are a real pain. Fortunately, you do have the option of just leaving them off if they get lost. The only thing that fails to work without them is the magazine safety and the bolt hold open, the gun functions fine otherwise. I have always been careful with them, so mine still works in all respects.
I really, really like this gun, a lot of fun, easy to shoulder, great balance, and amazingly accurate. However, anytime I clean it I am left scratching my head wondering how Walther ever let something get into production with such obvious flaws that would have been so easy to fix. It almost makes you angry how much potential this rifle had if they had just done it right.
