Users appreciate the Slick Sitemap plugin for its clean, elegant, and user-friendly visual layout, which is seen as an improvement over the traditional "bullet list" sitemap. They find it easy to use, flexible, and customizable, thanks to its menu-based structure. However, users report several drawbacks: it is outdated and incompatible with some WordPress functions, has unresolved support issues, and its CSS might interfere with other parts of the site. The plugin looks great on desktops but its responsiveness on smaller screens is questionable. Additionally, there are issues with the lines connecting buttons and potential complications with many pages making a horizontal or vertical layout desirable.