What I find the biggest advantage is the hardware (as another poster here does), but not only due to its superior capabilities in gesture recognition.

I have yet to find a non-Macbook touchpad which is:

- decently sized: all Windows/Linux laptops I have encountered have ridiculously small touchpads, some not even a quarter of a Macbook touchpad in size. I have huge hands, tiny touchpads are awful when two fingers are wider than the touchpad.

- decent material: AFAIK, Apple is the only manufacturer using a glass overlay on the touchpad. The Windows scene exclusively uses plastic, which gets greasy after a couple of months for me. For the keyboards it's similar, Apple simply uses a material that does not get greasy...

- decent layouting: MBP touchpads are nearly flush with the casing, which means one can use its full surface area including the edges. Windows touchpads all are recessed, worst I had was 5mm - as evidenced by the grease-free borders I lost about 25% of the already small touchpad.