not all that good, well, etc.

not (all) that (good, bad, well, poor, etc.)

Not especially or particularly (good, bad, etc.), especially compared to what one expected or hoped. The movie wasn't all that bad—you were making out like it was the worst thing in the world! I'm sorry to say this meal is not that good.
See also: not, that

not all that ˈgood, ˈwell, etc.

not particularly good, well, etc: He doesn’t sing all that well.
See also: all, not, that