Good Gear Guide
A closer look at the Sony PS4 and DualShock 4 cont...
If you place the PS4 on a flat surface there's no issue, but if you press down on it, the console rocks from side to side due to the fact that there's no rubber strip on one of the sides. It's not a huge issue and most people won't ever be pressing down on it, but it still seems like an odd design choice.
A closer look at the Sony PS4 and DualShock 4 controller