His works are excellent in both quality and quantity.
Tips
usage
Always preceded by two or more listed qualities — pattern is X 与/和 Y 俱佳 'X and Y are both excellent.' Common in reviews and praise: 色香味俱佳 (sèxiāngwèi jùjiā, 'color, aroma, and taste are all excellent') is a classic food-writing cliché.
memory
俱 = 'all / together,' 佳 = 'excellent / fine.' Think of it as a compact form of 'both/all are first-rate.'
