Two reasons this gets two stars: The translation and the formatting.
I knew I couldn't handle Canterbury Tales in Middle English, so this 19th-century translation seemed like a good bet. I can read 19th-century English very well, thank you, but this isn't 19th-century English. It's more like a stew of ancient and modern, and is difficult to comprehend without constantly looking up terms--terms that aren't in a dictionary. I'm not sure why Purves did this, except to give flavor to the words. I would suggest getting a translation that is completely in more modern English. The stories stand on their own, without (what seems to me) artifice.
But that isn't the worst of this edition. I know enough German that by reading aloud, I can understand the Germanic words. The worst is the way the text is formatted. In their opening notes, the formatters state that they took Purves' notes and put the glosses in the margin, flush right, and the longer notes at the end of each section. Nuh-uh. The glosses are NOT right justified, and are simply run onto the ends of the lines. If the definition is longer than the page is wide, it wraps either under the line or onto the end of the next line. This makes it extremely difficult to know where the poem leaves off and the notes begin.
Having the longer notes at the end of each section would be acceptable IF they were accessible by clicking on the numbers interspersed rather jarringly throughout the text. They aren't, and without an active table of contents, it is impossible to refer to the notes and back to your place again easily. In fact, there isn't even a button to go to the Table of Contents; one has to go to the beginning and page through.
I would so love to be able to move easily between the Prologue, which is Chaucer's summary of each character, and the tale each one tells, and to be able to refer quickly to the notes that explain some of the places and professions.