I have a similar document, but for writing references:
"I cannot recommend this man too highly. If you can get him to work for you, you will indeed be fortunate.”
For someone who is always skiving off: “A person like this is hard to find.”
For someone who drinks too much “I often felt he was wasted working for us”. Or “Every hour with him was a happy hour”
and finally “Nothing can describe the contribution that he makes....."