Early in his composing career Claude Debussy was an influence, and while some of his early works are somewhat in the style of impressionism, it was not Roussel's true voice as a composer. He had a highly classical turn to his compositional thought, which led him to more to the neo-classisist school of composition. He composed 4 symphonies and a few other works for orchestra, one concerto each for cello and piano, many chamber pieces, opera, ballet, and a handful of choral pieces. While his output was not large, he was a very influential composer in France between the world wars.
His orchestral music is not what is thought of as typically 'French', as it can have a 'bite' to it and a lot of rhythmic drive. His music sounds 'heavier', but not as heavy as some German orchestral music. The 3rd symphony opens with a first movement theme that is heavily accented and rhythmically terse. The contrast between this theme and the second theme is considerable, as the tune floats over the orchestra in muted colors until the first theme elbows its way back to the forefront. This movement is short for a first movement, at about five minutes, but with the total difference with the two themes and how they 'bounce' against each other, the movement manages to say what it needs to say, albeit in highly concentrated form.
The second movement is more relaxed in mood and length. At about 15 minutes, it is three times as long as the first movement and longer than the other three movements put together. But it does build to a loud climax and slowly returns to the relaxed mood that it began with. The third movement is a scherzo-dance that some have thought shows a Spanish influence. The last movement begins quietly, has a calm middle section, then the orchestra builds to a loud, crashing end.