Let's start with some photographs:
Note the sign: "No drinking in shelter, violators will be arrested."
.Looking down Park Avenue (reminds you of New York, no?) and the Parkside Neighborhood.
A few issues that jump out at me:Lack of seating - The bench in the shelter is large enough to fit one person comfortably, or two strangers awkwardly. Not to mention, there is often someone passed out on this bench.
Overall Size - This stop is always busy when I go by it in the morning (I apologize for taking pictures of it when no one was around). A larger shelter would be good for keeping more people dry and might make the area a bit more attractive. This stop serves three bus lines according to this map from the Metro website, and would make a great 'hub':
Aesthetic value: This stop is on a corner in a neighborhood that could use a fresh coat of paint. Why not start with a new shelter? This is a lower-income area and it sounds silly to represent neighborhood pride with a bus stop, but it would be a start. It's right next to Deering Oaks Park and a shiny new shelter could invite people to the area and serve as an information gatheringg resource with local maps, guides, advertising, etc.
Signage: The stops could use much larger and better signage of the metro routes. The current Metro schedule isn't overly complex compared to most cities, but the small maps that are on the back of this shelter could use some enlarging and clearer language.
Revenue: This isn't a walkability issue, but why aren't there any advertisements on our bus stops? I know Maine doesn't allow billboard advertising (I still have mixed feeling on this) but I don't see any harm in having a McDonald's ad on the side of a bus stop. It would bring in a little bit of much desired revenue for the system. I've even heard of larger cities which sell advertising rights on bus stops to private corporations and in return the company is responsible for the upkeep of the structure.
Here's an example of a pretty nice bus shelter, on Congress Street. This photo was taken from the side so it doesn't fully do it justice.
I think this shelter even features a heating component during the colder months. While it doesn't take care of several of my points I've mentioned, it does have plenty of seating and is large enough to serve the amount of people that use it. It also is unique and that counts for something. I don't want a clone made of this one, but it shows that Portland can have a proper bus stop away from the Pulse on Elm Street (the main hub).
And to finish with the Post Office bus stop... please fix it!