I believe The Beatles: Rock Band came the closest to being perfect. Eveything about that game was just beautifully done and the only things missing was Pro Drums, an option for Keys, and a few more Beatle songs (Hey Jude, Strawberry Fields Forever, Yesterday etc. etc.)
Had the same expectations for I am Setsuna, but from what I saw in gameplay and reviews, it was disappointing. Hopefully Sea of Stars will be a good one