1. Has no GUI elements. You can create you own using BBInterface. Or not use GUI at all (use only Bro@ms);
2. More faster! I wrote also plugin for foobar2k and this is better then to give commands through command line as in bbfoomp.
3. Besides standard actions it can also show Open, Add, AddFolder dialogs; change volume; seek current track; show title of track, formated as you want (see titleformat_help.html in foobar2000 folder); change track order (shuffle, repeate one, repeate all); start, show, hide or exit foobar2k.