To my untrained eye, Query Monitor looks like it provides a wealth of information. Unfortunately, I'm not 100% what I'm looking for when I look at QM's output.

For example:

Page generation time: What's a good time score to shoot for?
Peak memory usage: What's average? What's good?
Database query time: Am I slow? What's fast look like?
Database queries: How many is too many? How many is awesome?

etc.

It would be super helpful to see someone put together a basic "how to use Query Monitor" post to help people score and optimize their sites.