You know how sometimes you're walking up a really steep hill and you just kind of forget that you're going uphill because you've been walking that way for so long (said no one, ever)? Yeah, us neither. Walking uphill is hard no matter how often you do it (thanks a bunch, gravity) and any hardcore hiker will tell you it's incredibly dangerous to lose focus while on a climb or underestimate the danger and power of a mountain.
With poetry, it's a little different. Rossetti tells us in the opening line that "the road winds up-hill all the way," but all that talk about beds and the inn in the second half makes it sort of easy to forget the incredibly difficult, uphill path you take to get there. By titling the poem "Up-Hill," she provides her readers with a constant reminder of the path at the beginning and situates the inn as the super-awesome reward at the end of a hard journey, as opposed to something you can stumble across without trying. Calling the poem "Up-Hill" also gives Shmoop the chance to point out that the word "Up-Hill" as it is capitalized in the first edition kind of looks like two mountains (the U and the H) with a valley in the middle (the dash). Sure, it's a stretch, but we still think it's pretty cool.