What should I expect from learning Brazilian Jiu Jitsu?

That relies largely on the practitioner. If you practice inconsistently, then progress in BJJ will be slow and frustrating at best.  However, if you can come to class at least 2-3 times per week, BJJ can transform your life. BJJ is a grappling martial art predominantly, if you can handle someone actively trying to submit you on a regular basis and return the effort, then your perspective on most social interactions changes for the positive – you become hardened to adversity. You will become confident that you can defend yourself and physically you will become stronger and healthier.  Life starts to seem easier as you will look better, feel better and have a new confidence throughout your daily life.