Don’t exaggerate -- show where and how they can improve. Don’t put the candidate on a pedestal. Not only does it not look plausible, it will also set expectations for them that will be next to impossible to meet. If they have an Achille’s heel, don’t exaggerate it, but don’t hide it, either.
How important are letters of recommendation? Letters of recommendation are required for almost every graduate school application and are a very important part of the application process. Usually grades and test scores factor in most heavily; however, your letters of recommendation could be the deciding factor in the admission process.