Short Version of Review: The switch did not resolve the issue I was experiencing, but I cannot fault the product. Thus, I will not leave a negative score, as I think others who are certain they have a faulty / damaged power switch should test the product more carefully than I did and make up their mind about its functionality.
Long Version of Review: I acquired a Game Boy Color with power continuity issues on the motherboard. I traced the issue to the flow between the SW1 VCC point on one side; the power was not getting transferred from SW1 VCC to the power switch on the opposite side. I temporarily resolved this by running a wire from SW1 VCC to the "C" solder pad on the power switch. The problem? This permanently "opens" the switch, and whenever batteries are inserted into the console, it immediately turns on. I was hoping to complete an internal rechargeable battery mod on the console, and thus, a constantly open power switch would not due. Opining that the transfer of power from one side of the board to the switch might have been a dirty power switch issue, I removed the original power switch and cleaned it. However, in trying to reassemble it, I broke the switch beyond repair - enter the Helder Power Switch.
The switch is solid, and the concave solder point connection design makes it easy to solder to the motherboard. Unfortunately, after soldering and testing a few times, it did not resolve my power transfer issue. Curious about the switch's inner construction, I removed the cover that secures the small plastic toggle itself. In doing so, I discovered that the plastic of the toggle is quite brittle and it broke rather easily. Of course, the switch is not designed / intended to be disassembled, so I would not recommend doing this. At this point, I decided to completely remove the switch from the board - and lifted one of the power switch solder points off the board completely. Not my finest hour in Game Boy modding, but I can't fault the product.
If you have a GBC motherboard where you are absolutely certain the power switch is faulty / broken and you have no other options to replace it (i.e. no other consoles from which to harvest OEM parts), give it a shot. Just be (more) careful (than I was).