The phrase can reflect personal taste, so what's 'not up to much' for one person may be fine for another.

Subjectivity

It doesn't mean something is terrible, just that it doesn't stand out positively.

Not Awful

It's often used to politely express disappointment or that expectations were not met.

Describes someone's personal condition rather than an external item or event.

Implies honesty about not being well without causing too much worry.

Used when the speaker doesn't want to give details about their health.