You know when you have arrived and you know when you have left. This is very important for establishing neighborhood identity. Great neighborhoods don't go on forever. They are limited in size. The convention established over many years is that the neighborhood size is defined by a 5-minute walk from the center to the edge.
Great neighborhoods have a mix of land uses and building types.
Great neighborhoods have a variety of building sizes and types of residential dwellings to own and rent, thereby insuring that diversity is built in. Great neighborhoods have a connected, integrated network of walkable streets. You cannot have quality urbanity without this. This principle is the most important. In great neighborhoods, the prime, most visible property is set aside for parks, squares, plazas or civic buildings.