Yes, well, Mary Monroe. Hard taskmaster and takes no nonsense from her students. You might find yourself leaving the lessons shaking.
That said, however, you cannot help but feel you are in very capable hands. She is exceptionally knowledgeable, and will iron out any problems instantly. Lessons are bi-weekly so you have plenty of time to practise... and God help you if you don't.
When you get to know this remarkable lady better, you realise that she actually has a warm and friendly personality--it's just that in lessons she is professional and straightforward. None of her expectations are unreasonable, and if you work with her seriously, you will make steady and solid progress.
She's also the only Organ teacher at Columbia, so if you're reading this review in the hopes of finding an alternative, you're wasting your time... but you might find it useful if you're a pianist thinking of giving the organ a try. On balance, I do recommend her, but be warned: don't mess with her, and don't take organ if you're not really serious.