I've been taking her Callan class since I had started QQ.
I've also taken classes with other teachers, but her pronunciation is the easiest to hear and speaking speed is comfortable for me.
The thing I'm always looking forward to in her class is a small talk before the lesson.
(Of course she will skip the small talk if you'd like to proceed the lesson quickly.)
Although I cannot continue anything long before, now I can continue QQ English because she keeps me entertained!