Be no great shakes
Definition 1 of 1
Pro Tip 1/3Informal Tone
Use 'be no great shakes' in casual conversations rather than formal or professional settings. 
I tried the new restaurant; it was no great shakes.
Pro Tip 2/3Negatively Skewed
The phrase suggests a negative opinion but in a mild way, without harsh criticism. 
She's no great shakes at dancing, but she enjoys it.
Pro Tip 3/3Subjectivity
Understand that 'be no great shakes' expresses a personal view, which others may not share. 
Joe thinks he's no great shakes at chess, yet he often wins.