I have tried my Park Assist a few times. For perpendicular parking, it has actually detected a space a few times. For parallel parking, I have never gotten it to detect a space, so have never seen it actually steer my truck into a parallel space.
The first time it actually detected a space, it tried to back me into a minivan. I mean, I was using it to park perpendicular in a row of spaces on my right. Except, where it told me to stop and then start backing up, the space it was trying to put me in was between 2 other cars, but the space had a minivan in it. I mean, there was no empty space anywhere close. I kept going until my bumper was just about into the minivan, just to make sure I wasn't incorrectly second-guessing the Park Assist.
Since that time, it has correctly put me into a perpendicular space a few times. One thing that is kind of annoying is that it puts you exactly (more or less) in between the 2 cars on either side. One time, the car on one side was parked on the far line of their space. So, I ended up almost on the line of the space I was in.
My problem with testing it for parallel parking is that everywhere I have been so far, I have not found a space with a car on either side. It's always been a space that is either a cutout in the curbing, so no parking space in front or behind, but still a car-sized hole you have to fit into to park. Or, it has been a space with the curb cutout at one end and a car parked at the other end of the space. So, still not two cars to fit in between.
What I have had several times, though, is driving along a row of perpendicular spaces and the PA simply not detecting an open space. So, I abort and just park it manually.
Again, like others have said, I don't NEED the PA. But, I paid for it and not only do I want it to work, I want to know HOW it works. I want to be ABLE to use it competently, in case I ever feel a need to for some reason.