A good COMPASS score for a single section of the test depends on which section it is. For the reading section, a good score is 88. For writing, 65 is considered a good score. For math-related sections, a 70 or higher is considered a good score.
Often, scores for multiple sections are combined to determine aptitude for college-level courses, which is the purpose of the COMPASS test as a whole. For example, the combined score for the reading, writing and listening portions of the test is often used, in which case a 260 or higher, out of 300, is considered a good score.