AdvantagesYou can make your own songs.
DisadvantagesSongs are usually too big to save to the standard memory card.
AdvantagesIt exists, very popular, good size for clarity, some well known songs for piano, timeless.
DisadvantagesCan be a struggle for amateur players, a bit pricey, smaller condensed book would be handier.
AdvantagesJeff's very early stuff, Some classics before they became finished, A hitoric looks at Jeff's past
DisadvantagesSome songs really are demo quality