Odd that many in this thread blame performance reviews themselves ("complete and utter waste of time", "waste of time and simply busy work", etc) and not the manager giving them.
For your manager to do it right requires some courage (to give negative feedback), maturity (to do it professionally), training (e.g. never deliver feedback in 'the compliment sandwich') and empathy (to relate to the employee's POV). Obviously most managers lack these.
E.g. Some employees are over-eager and blitz colleagues: "Hey did you get the email I just sent 30 seconds ago?" Others like to have Jira ticket comment wars. A good manager would give direct feedback routinely throughout the year.
"Hey Bob, blowing up my inbox with dozens of IMs and emails in a single day is counter-productive."
"Hey Suzy, that 750-word Jira comment about why your dispatch function to the React store is a better approach then Duane's could have been better handled face-to-face."
Then the performance review is hopefully a boring, pedestrian summary of stuff talked about all year.
Instead managers are afraid to give feedback and wait until January to tell you all the things they hate about you. Plus your review is likely tied to your compensation/promotion, often making it unnecessarily a high-stress, do-or-die bombshell.
What's really important these days (IMHO) is not the review itself since nowadays everyone changes jobs like they change pants, what matters is your ability to receive negative feedback like an adult and adapt. It means having a manager who can give negative feedback like an adult (a big if) but that will likely help you more in your career than generic pats on the back.
Happy review season everyone.