Basically, writing a review on anything is subjective because you are appealing to your own ideas, appreciation or impression. While it is given a review writer should base what he writes about something he had first-hand experience with, he should be able to give objective facts and not depend on his own thoughts.
Again, writing a review is subjective but a reviewer should base his subjective perception on the objective facts and confirm or deny them based on his experience.
The best example of this is when you are reviewing a car in which the engineers who designed it say it can reach up to 200 miles per hour. The reviewer should, if allowed to do the test drive, see if it can indeed reach up to that top speed. If so, only then a reviewer could confirm that the car lives up to the expectations.
Again, writing a review is subjective but a reviewer should base his subjective perception on the objective facts and confirm or deny them based on his experience.
The best example of this is when you are reviewing a car in which the engineers who designed it say it can reach up to 200 miles per hour. The reviewer should, if allowed to do the test drive, see if it can indeed reach up to that top speed. If so, only then a reviewer could confirm that the car lives up to the expectations.