Highly regarded as the best Street Fighter by fans of the series, it fine-tuned everything that SF III needed. The roster wasn't major, but it included the essential characters in the series. Background designs were so beautiful they could distract from the fighting taking place of the already gorgeous character designs. Don't forget the music that even took it up a notch from the already irresistible tunes from the Alpha series.
SF IV tried to improve the series, but simply put, SF III may always be the perfect installment of the Street Fighter franchise that didn't need improvement.