After the disastrous launch of the original Microsoft Surface RT, it's hard to imagine that five years later the Surface brand would be attached to a full line of PCs and peripherals that together make up a billion-dollar business for Microsoft.

The Surface Pro 4 is a refined version of the original Surface Pro, which I called "brilliant, quirky, and flawed" in my original review. It's still brilliant and quirky, but the flaws have been mostly engineered away.

In a testament to how well the Surface Pro has defined a category, consider the number of imitators it's spawned, all with their own takes on kickstands and detachable keyboards.

RELATED