This is a total noob question, but I can for the life of me turn down the speakerphone volume. I set the in-call volume to its lowest. I tried hitting the volume button to lowest setting during a call, but the speakphone just remains obnoxiously loud.
On the other hand, my ringtone is quiet as a mouse. WTF?
UPDATE: It seems that if you crank the volume way up THEN turn it down, it will work. Stupid minor bug.