My time interviewing with Facebook was one of the best recruiting experiences I've ever had. Everyone was kind and supportive through the process, and the atmosphere was generally comfortable. I attended a Facebook event at my university. I started off with two brief portfolio reviews, followed by 1 interview to critique an app. After that, I was brought on site to knock out 5 interviews with current product designers and a product design manager. In my process, I found it important to focus not just on the experience in the context of the projects that you're showing, but also in your interactions with the team. Listen carefully and think through your design decisions in the exercises. Demonstrate your empathy and understanding of the product space. Prepare yourself well! The onsite interview is very exhilarating and intensive so make sure you're well rested before a day of great conversations.