There are many cons to ANKI with the biggest being time. Another is that if you suffer with switching tasks you might be drawn to ANKI because it's a monotonous task but you'll end up ANKI'ing every little thing which is incredibly inefficient. I'd imagine (because I don't use anki) that the best users know when to and when not to make a card and when to go to re-read something, work things out on paper, or seek help when they don't understand something rather than blindly making an ANKI card they don't understand.
That being said, and to answer your question, ANKI cards are not the ideal way to learn concepts, but also the concepts in medical school are not that difficult. Concepts are better learnt by spaced-repetitional application as opposed to spaced-repetitional recall. Therefore, focus more on study groups where people are often confused and ask questions, practice problems, problem solving on separate sheets of paper, etc.