A makeup artist review should be an honest account of your experience with the artist. It should include both the good and the bad, in order to give potential clients a well-rounded idea of what to expect.
When writing a review, be sure to focus on the artist's strengths and weaknesses. For example, if they did an amazing job with your eye makeup but you were not thrilled with their lip color choices, make note of that in your review. Similarly, if they were very personable and made you feel comfortable throughout the process, be sure to mention that as well!
The most important thing is to be honest - after all, this review will help others make informed decisions about their own makeup artists. With that in mind, go ahead and share your thoughts on the artist's work - good or bad!