If you live in the 'hood and missed signing for a package, this is the place you will be sent to pick it up. Which is funny considering the big huge fancy post office is just a block away, but for some reason they have the racket on picking up packages that have had missed deliveries.
This is a nice little postal outlet, the lines are usually short and the staff very pleasant. They have some fun items like postcards and your usual mail supplies, as well as some photo developing and other services. I generally only go in when I need to pick something up or when the line at the big post office is too long.
They seem to have a few things on sale there that are a bit overpriced for sort of generic/outdated novelty mailers and such, but I think if you're there with a specific purpose you won't likely be sucked in by them anyway.