I have put 6-700 rounds through my P11 and I have only had a few malfunctions, the most common is not fully chambering a round, all it takes is a tap on the back of the slide. only other one was due to ammo, had to let the hammer hit the round a second time to get it to fire.
as a basic firearm there is nothing fundamentally wrong with the kel-tec's I have owned the PF9, everyone I let shoot the gun did not like it and had a very hard time being accurate with the weapon. the triiger pull is very long and harsh making most pull the gun either low and right or low and left. not an ideal situation in a self defense situation. I know the trigger can be reworked to make this better but I also did not care for the feel of the weapon. just couldnt get comfortable with it so I opted for something else. I personally chose to spend a little more on my personel protection weapon of choice. I know there are many that are completely satisfied with the kel tec and that is great its just not for me.
I just finished shooting a second IDPA match with my P-32. I came in 18th overall out of 40+ at the 1st one and 16th overall out of around 40 at this one. One reason is because it doesn't malfunction. Would I rather rely on a G-19 or something comparable? Sure, but sometimes due to my work situation, it might be all I can get away with when stopping somewhere before or after work. When carrying it I worry more about effectiveness, limits on what it's capable of and situational awareness. Worrying about it functioning doesn't enter into the equation.
My PF-9 has been great. No failures of any kind, but haven't shot it as much as my other 9s yet either. It is small, light, thin, but also has a nasty trigger, it's hard to shoot well, snappy recoiling, uncomfortable to handle, and ugly; but like GTG said, it works. For sub $300 it's hard to beat.
I had one in .380 that was stolen a year ago. Of all the guns I own that is the one I was happiest about being stolen. I bought it new in 2007 and it was unreliable out of the box with ball ammo. It jammed more than it shot. So I returned it to Kel-Tec and they worked their magic on it. I got it back and it didn't jam nearly as much. Only a few times every time I shot it.
So, I'm back strictly to Glocks & 5-shot S&W and Taurus revolvers.
I think it says right in the manual that you should shoot them at least 200 rounds minimum before relying on the gun in a SD role. If this was all I had at the time then yes I would trust my life to it. I carried one for awhile and still have one but I have gotten use to just carrying a j-frame in my front pocket or on my ankle and trust it more. That is when I am not carrying the Glock 26 or going Magnum PI and carrying my 1911.