The ability of creating courses, quizzes etc is great! I can't think about anything that could be improved or changed at this point in time as it's been very good so far!! We are using bridge tracker primarily because we have many clients with different needs/skillsets who need tailored solutions - they would not get what they want if you just give them one set solution (like Moodle).
This has helped us solve problems like having too much content but no way how people will know where exactly to find things when needed; solving student-teacher communication issues by providing an online platform which students use themselves without needing teachers' help all day long.