Yin might be the hardest yet most wonderful yoga class you will ever take in your life. Unlike the vinyasa flow classes, each posture is held for about 6-8 minutes, so there are a very limited number of postures done. Yin actually moves bone over time, making it incredibly healing and beneficial for every person to start at any point in their life. A very meditative, calming experience.
You may want to have a blanket that you can roll up, a bolster, or a block.