I think the biggest factor enabling the Surface Pro 3 to replace a laptop is the 12-inch screen. The 10-inch display on the first two generations was wonderful,

I think the biggest factor enabling the Surface Pro 3 to replace a laptop is the 12-inch screen. The 10-inch display on the first two generations was wonderful, however I always felt it was a tad bit too small for getting real work done. Although it's now possibly large for a tablet, it's nicer to use than the first and second generation models since it's lighter and thinner.