I really think the majority of firearms that have problems are attributed to user error in one form or the other. Improper cleaning, grip, ammunition etc.
I can't really say I've had a problem before. I think that some firearms have inherently worse designs than others that make them less reliable.
The PF9 and LCP don't seem to be as reliable as a larger pocket pistol like the G26.
Out of 3 M&P's I have purchased, they have each ran FLAWLESSLY out of the box with ANY ammunition. I absolutely love them.