The Flute has the purest tone of all the woodwinds, nearly a sine wave. It is very agile and often plays rapid scales and trills with great ease.
The lower register is characterized by a dark sound and cannot project through a thick orchestration. Tones below the notated D will likely be lost within the ensemble. The upper register is quite brilliant, with the highest notes being easily in even the thickest orchestration. The high A and above can be very cutting. For orchestration, the flute is one of the few instruments that regularly performs well above the staff.
The lowest note (B) on a flute is only on flutes with a "B-foot", and is not recommended outside of solo repertoire. The Piccolo Flute sounds an octave higher than written, and is incredibly high. When used within the orchestra, it should be used sparingly. The lower register can mimic the penny whistle with a "folkish" sound. The Alto Flute sounds a fourth lower than written and is darker in timbre. It will not cut through the orchestra, and is rarely written for anything outside of a flute ensemble. The Bass Flute sounds an octave lower than written. It has even less projection than the alto flute.
The flute does well doubling the violin and oboe at pitch, and the clarinet at an octave. It can be used lyrically to great effect, due its pure tone and vibrato.
In addition, due to the large amount of air required to play the instrument, lengthy phrases are difficult to play in one breath