It can be. Depends upon how steep the roof is and your ability to climb.
It does take a few special tools however to tighten up the standing seams and a few ladders to place on the roof. As you do not want to stand directly on the roof or it will bend. This results in poor seaming and possible future leaks.
house...shed...what type of structure is this. Metal roofing can take on many forms...some are much more friendly to install.
check out this article I wrote