Why the Norton edition -- which preserves these tales in their original Middle English dialect -- over the modernised versions of Chaucer's classic stories? Because it's only in their original form that they retain the poetry and power of Chaucer's intent. I read these stories with a professor who could passably read Middle English and it was a revelation. Before, with translated versions, I had never quite understood why Chaucer was considered so great, so necessary to the canon. Hearing them in the original form, I suddenly understood. The tales are funny, dirty, odd stories (like an English version of "The Decameron") told in striking, blood-stirring rhyme and rhythm. Hearing them read aloud was like music to the ear. Which makes the smoothed-over versions feel flat and dead to the ear.
Buy this edition. Try to learn enough Middle English to get along. Discover for yourself the power of Chaucer's poetry.