Having a quick look at something, easy with mouse and keyboard, takes a good deal longer with the controllers. But considering how often you use your Pip-Boy, it begins to feel like a bit of a chore after a while.
At first it's cool to hold your wrist up to your face to activate the screen (it enlarges automatically, though since you have no arms it's just sort of floating there) and scrolling through the options using the directional pad works okay after a little practice. The Pip-Boy, unfortunately, doesn't translate quite as well.