I picked up a Ultra Compact late last May. With the factory mag, it wouldn't feed worth crap, and the slide didn't lock back after the last round. So, I forked out for a couple of Wilson Combat mags. That solved the feed problems, but the slide still didn't lock back. I also found that, if I manually locked the slide back and shook the weapon, the slide would slam forward. I called SA and made arrangements to return it for warrantee work, but decided to keep it until I finished a handgunning class I'm scheduled to take next Monday. Yesterday, I found that I couldn't disengage the thumb safety. On further inspection, I found that the plunger tube is pulling away from the frame, causing the safety plunger to come out over the thumb safety.
I'm waiting for a call back from SA now. I'm not all that far away from the factory, and am hoping that they can do something to make this right before my class Monday. Otherwise, I'm out a hundred and ten bucks in tuition. I do have to say though that they've been pleasant and responsive on the phone so far. We'll see what happens.
The moral of this story? Don't buy a ultra compact if you need it to function out of the box. From what I hear, they'll put any problems right under warranty, but I guess trips back to the factory are pretty common.