With each generation of the Surface Pro, Microsoft gets closer and closer to fulfilling its promise of a tablet that can replace your laptop. Last year's Surface Pro 3 was certainly powerful enough to take on similarly priced notebooks, but the keyboard wasn't as comfortable, and it wasn't particularly easy to use in your lap either. Fortunately, the new Surface Pro 4 mostly addresses these flaws, with a sturdier keyboard, improved pen and slightly lighter design. Unfortunately, the battery life is about the same as last time, delivering just over seven hours of video playback in our tests. If Microsoft were to extend the runtime and include the keyboard dock in the box, we'd be inclined to give the Surface an even higher score. Even as is, though, we can finally say it's well-rounded enough to replace a laptop.