I've carried a Kel-Tec P2-AT for a couple of years as a BUG. There's no doubt that they are not the "fit and finish" of guns like Sig, HK, etc. They are inexpensive and small. Most consider a firearm in this size and caliber as a "weapon of last resort".
A firearm like this is only accurate out to about 25 feet. With it being essentially a "close in" firearm I don't see the need for hours and hours of practice. Just pull, point, shoot. As for reliability, they definitely do have some issues until either broken in or "fluffed and buffed". I stripped mine down when I brought it home. With some 2,000grit sandpaper, wrapped around a dowel, I removed the machine marks from the feed ramp. Using the same paper with a popsicle stick I did the same for all the other machine marks on slide and flat barrel surfaces. The finish after the 2k grit sandpaper work is good enough but I finished up by polishing the feed ramp to a mirror finish with some rouge and a dremel.
For just over $200 I have a very reliable backup pistol that fits in a shirt pocket, pants pocket, or a small IWB holster. I also like to carry it in the front pocket on the "bib" of my Carhartt's. With the clip (not the magazine, but the pocket clip) installed it looks just like a small tool clip on the outside of the pocket.
For a real gun I carry a Sig P-229 or CZ75 SP-01. As for the Kel-Tec? Let's just say that it goes a lot of places that anything larger would not be practical (wink, wink)