There's only one Circulator that stops at the Navy Yard. It's clearly marked. They have no numbers - destinations are clearly marked, and Union Station is the defacto hub - you could change to a bus headed for M St in Georgetown.
On a day like today, I think it was faster. No crowds. I got a comfy seat to slump in on the Red Line at Union Station before all the damn Phillies fans got on in Chinatown. Very friendly bus driver and passengers. They run every 10 minutes so no need for a schedule, and they run till midnight on Nats game nights.
I think the praise is pretty warranted. They ran during the blizzards when Metro was down (but I didn't ride so I can't attest to frequency or quality of ride during the storm).
I don't really live in PA anymore - thought it was becoming apparent from my posts