Of course you should! This is a case of nearly nothing to lose (a bit over two hours of your time) and everything to gain. You’ll become familiar with the exam, and what it’s like to sit in the testing room. You’ll discover what your strengths and weaknesses are, with no pressure.
A lot of sophomores skip the PSAT. They say: “But my friends aren’t taking it,” “I don’t want to be bothered,” or “I’ll think about that stuff next year.” Don’t fall for these cop-outs. When it comes time to take the PSAT as a junior, you’ll be glad you have the experience.