BK Blog Post
Posted by Jeevan Sivasubramaniam, Managing Director, Editorial, Berrett-Koehler Publishers Inc.
Good is an adjective that describes something; if you did a good job, then you do good work. Well is an adverb that describes how something was done; you can do your job well.
Where it gets tricky is when you describe, say, your health or emotional state. "I don't feel well" is grammatically correct, even though many people often say, "I don't feel too good." On the other hand, "I don't feel good about how he treated me" is correct; no one says, "I don't feel well about how I'm treated."
Confused? If you're praising an employee and referring to the outcome say, "You did a good job." If you're referring to how the employee performed say, "You did incredibly well."