Our current house is like that. And in house shopping we are focusing on more neighborhoods that are planned the same. Aesthetically speaking, It looks
so much nicer not to have driveways and cars in sight when you look down a street. Also Never have to worry about a car blocking a sidewalk or backing out over your kid riding his bike down the sidewalk.
We have a decent "courtyard" as it is called...it is just on the side of our house, not behind. We even have a swingset for DD3 in it. And since it is between our house and the house next door, no one can look into our yard, like if you had a backyard neighbor.
We love it....but it is Charleston-style of course, so that is probably why. Can you imagine rainbow row with driveways in front???
ETA: Oh and the other thing about alleyway communities, is that they are done to promote front porch living. All the front steps lead straight down to the sidewalk. All the houses have big front porches where people linger and sip sweet tea and chat with neighbors as they pass by. It is like Mayberry.

...at least around here. But everything is new and communities are master-planned, around here.