If I woke up with just 5 inches, I'd first sleepily look around under the bed for the rest of it. But two of my favorite, best lovers, and men who I deeply miss had about 5 inches. Never bothered me. A penis is a penis is a penis (to paraphrase Gertrude Stein).
I can't speak for straight men, but as a mostly gay male I find 5 inches great to suck on. And where I grew up in the Intermountain West, 5 inches is about the norm and attached to a lot of hot-looking men.