Nothing if not
Definition 1 of 1
Pro Tip 1/3Emphasis Added
The phrase adds strong emphasis indicating a noteworthy quality or aspect. 
Her performance was nothing if not breathtaking.
Pro Tip 2/3Subtle Contrast
Often used to introduce a subtle contrast or to acknowledge a negative quality while stressing a positive one. 
He is nothing if not persistent, despite his lack of experience.
Pro Tip 3/3Understatement
Sometimes it underplays the quality being highlighted, functioning as an understatement. 
The dessert was nothing if not delicious, though it looked quite simple.