PDR is a requirement in some departments. In others it's optional. Check your department’s policy.
There are a number of reasons why people aren't keen on PDR. It may be that you don’t feel comfortable with the idea of your work being "measured" in some way. Perhaps your previous experience of a review process has been difficult. Or perhaps you can’t see the point because your work doesn’t change much and you can’t see how objectives can be set.
Remember that the opportunity for a regular and structured discussion with the person who has line management or leadership responsibility is fundamentally good practice. Institutions that give their staff an opportunity to talk about their work, offer and hear feedback, set realistic objectives and discuss their development are likely to be more effective workplaces. (MacLeod, D. & Clarke, N. 2011, Engaging for Success, Department for Business, Innovation and Skills)
And at the very least, PDR gives you the chance to talk about yourself, how you feel about your job and any factors that affect your work.