I had a PF9 and initially loved it. I purchased it when the model was relatively new to the market, early 2007.
The size and weight were perfect for my needs. I bought a neoprene Uncle Mike's ITP holster for carry and it fit like a glove. On the range, it was about as accurate as something that small could possibly be expected, and suited my needs for short-distance targets.
Fast forward about three years and perhaps 2000-2500 rounds of ammo (for the record, I never used any "cheap" or off-brand ammo in it). This pistol was not abused, but one day when disassembling it for cleaning, the rear sight basically crumbled off in my hand. Perhaps it had a bunch of hairline fractures; I am not sure because it was too late by the time it broke. A friend of mine got me a replacement rear sight and I was happy.
Then about two months later, I was on the range and had a strange sort of jam. This pistol had never misbehaved before and the slide was suddenly stuck in an odd position after it ejected and then began to travel forward to chamber the next round. I cleared it and inspected it. For lack of a better way to explain, the piece of the metal frame right behind the hammer had broken off. I am guessing it was caused by the hammer traveling back with enough force, enough times, to eventually break that piece. That was the end of my KelTec experience, I did not end up replacing the PF9.