Quantum mechanics varies in difficulty based on factors such as the university, lecturer, course material, and the student's math skills and prior knowledge. It is often perceived as complex and bizarre, with notable quotes highlighting its challenging nature. However, focusing on practical calculations before delving into philosophical interpretations can make the subject more manageable. A recommended approach is to start with resources like Griffiths' textbook, which emphasizes problem-solving before addressing more abstract concepts, making the learning process smoother and more accessible.