Waterhouse lived and painted from mid-1800's through early 1900's. His subjects included figures from mythology, Roman and medieval history, literature such as Shakespeare and Tennyson, and women with flowers, as well as commissioned portraits.
His style was basically sketchy, paintings often still showing sketch lines, or deliberate outlines. He painted faces in smooth detail, while clothing was more sketchy, and backgrounds were sometimes done quickly as a loose oil sketch (see The Necklace for extreme example). He was certainly capable of painting in a more detailed consistent manner, as his masterpiece, St. Cecelia shows. This painting took him two years and sold for over $12,000,000--the highest price ever paid for a Victorian era oil painting.
He often chose color themes for many of his paintings, doing one in blues and oranges, another in shades of blue and gray, another heavy with browns and beiges, or bright with violets and pinks, etc.
Below are many of his oil paintings, along with a few sketches, and one watercolor, The Flower Picker. My personal favorite of all Waterhouse paintings is Windflowers, followed by Soul of the Rose.