As with its English cognate, I know the denotation ranges from "poor, disappointing" to "run of the mill, average, nothing to write home about".
In English, the connotation is on the negative end of that spectrum: mediocrity is implicitly opposed to excellence.
I wouldn't recommend the cupcakes from that bakery. They're mediocre.
What is the connotation in French?
Particularly interested in Canada but ready to accept answers based on other varieties.