U.S. Post Offices aren't known for their prompt, courteous service and this one is no different. Plan on a long wait in line and for it to take a long time to complete your task once you reach the front (regardless of what you are having done).
Two nice things about this location are that:
1.) There is an automated machine for sending boxes. It's a great service if you know exactly what you need, but is not intuitive and will not tell you your "best bet" for sending your package in a timely manner.
2.) There is a woman who helps people in line suggesting they fill out forms before they reach the front. She will help you find the right form, but gives little more advice than that.