I will avoid hubris by not attempting to rate "the Odyssey" per se! My five stars are for the translation by E.V. Rieu in the Penguin Classics edition, updated by his son and Peter Jones to make it even more readable for the current generation. The transparent, joyful prose makes this a superb experience for child or adult. It doesn't read like a translation. There is no tortured struggle with the Greek. There are no King James' bible archaisms. I can't see how it could be made more accessible or joyful for modern readers. If a teenager watches a film of this epic and asks for the "book version", give them this this! They will instantly get the message that the film version is never better than the original book.
One reviewer had trouble digesting some paragraphs. Were they reading a different translation? I had little trouble digesting this; the only (slight) difficulty was with the large cast of characters. Greek Gods are dropped in without much explanation, and as I'm not an expert on Ancient Greek Myth I needed some help with placing these endlessly interesting characters. Fortunately the editors provide a superb glossary! This gives you a short sentence about every place and person involved -- no more or less than you need to get on with the story.
Rieu's translation was the first of the Penguin Classics,the series which he and Sir Andrew Lane founded. His aim was to translate classics into good modern English. So I guess he thought he had to to a really good job on this first book. And he did! The vision of founding the Penguin Classics came to him while translating the Odyssey aloud to his wife and daughters while bombs dropped on London during the blitz. You might call him "the ace who launched a thousand books".