It would be impossible to talk about Eternal Sonata without first mentioning its visuals. Cel-shading is nothing new to videogames, but Eternal Sonata is one of the first (of the games released in the US anyway) to really try and push the style into the next-gen arena. The level of detail found in each of the game's characters and locales is unmatched. The rich visual style is enhanced by the game's use of bright, rich colors that make everything about the game "pop" and will really make you glad you shelled out the money for an HD set.
Audio is no slouch either. While Chopin's music doesn't take a central of a role as you would expect, they do pop up where appropriate - mostly in the "real world" sequences that hold the game together. Though the rest of the soundtrack does sometimes slip into the "traditional" Japanese RPG style, it easily stands out as one of the best. The various tracks fit the mood and look shown by the visuals.
Voicework is mostly good, though it does feature its fair share of annoying voices. Most fit their characters, though some do tread close to being annoying. Purists will be happy to know that the original Japanese voice tracks are available.