no great shakes
From Longman Dictionary of Contemporary Englishno great shakesno great shakesspokenBAD AT not very skilful, or not very good He’s no great shakes as a singer. → shakeExamples from the Corpusno great shakes• It is very simply made and no great shakes as a piece of cinema.• Secondly, and crucially, Professor Griff is no great shakes as a rapper.• He's no great shakes as a singer.• At school I was no great shakes at it, or anything.