Seriously? You get to be entirely unseen for five solid minutes? And you consider that useless? What the hell do you want to do? Make the rogue entirely obselete, and dance your way down the hallway in plain sight rather than use the spell to augment a plan, making the challenging parts doable.
Suppose I want to eavesdrop on someone and find out just exactly when the One Ring is leaving for Mordor? 5 minutes won't cut it unless I'm EXTREMELY lucky. And why is the rogue obsolete? As others have said, it's more than likely the rogue who's gonna be the recipient of the spell.