Coming from a rMBP 15", I found the SP3 touchpad was too small for me to use comfortably. But it was still usable.

Now that they have increased the size of the touchpad and made the keyboard better, I actually have a bit of a dilemma. You can customize the SP4 preorder with an i7 and 16GB of memory for cheaper than the Surface Book i7 with 8GB memory. I'm not sure how necessary the Nvidia card is for my purposes.