U is for Unhappy
Happiness should be essential for any employee. An appraisal can be an opportunity to talk about what makes you happy (and what makes you unhappy).
This might be talking more about what work you like doing and asking for more of it to give you a better balance.
This might be talking about what you would like your boss to stop doing (or start doing).
This might be talking about what you need to do your best work.
This is not a moan or complaining session about everything that is wrong. Treat is in a positive manner.
Therefore if you have issues that you want to raise it is important to thing about them beforehand and prepare. Think solutions.