Few things in life create emotion in a person like music does. Emotions are a very subjective experience. Music to one person can mean something totally different compared to another person. Reviewing music requires a unique blend of subjectivity and objectivity. Balancing being objective and fair while also letting your personal feelings and emotions shine through in your writing is an art all to itself. The best method as a writer to balance the two is to be honest and truthful with yourself and let your writing be a reflection of that.
Take reviewing a jazz concert for example. You might not like jazz music but are still required by your employer to review it. In this case, you will need to do a careful balancing job between expressing your subjective feelings that jazz music is not your cup of tea, with being objective. Keeping an open mind is of utmost importance. If you do not like a song, do not go on a tirade about all the issues you had. Instead, show that you have an informed opinion about it. Explain why you did not like something.
Also remember that just because you like something does not automatically mean it is good. The same works for if you do not like it. This does not automatically mean it is bad. It takes a careful and delicate method of thinking and writing for a writer to be objective and subjective when writing. Do not let your emotions take over. Be reasonable and keep an open mind when reviewing and your readers will greatly appreciate it and trust you for it.