There's not much more I can say after reading the reviews below, except to agree that this is _the_ book to own if you're wanting to add William Blake to your library.
This is a large book, clocking in at around nine hundred pages. Within you'll find all the great poetry that makes Blake, well, Blake. The "Songs of Innocence and Experience" are truly wonderful, as is "The Marriage of Heaven and Hell".
Lots to read here beyond than the known works, including miscellaneous poems, songs and verses and sataric verses and epigrams, even letters that Blake himself wrote.
The book is neatly organized and easy to navigate, making the section you're looking for a snap to find. At the back of the book are sections with textual notes (a small "t" is marked throughout Blake's works), and commentary (a small "c"), also marked. Invaluable resources to help understand and navigate the complexity of Blake's poems and prose. An index of titles and first lines is also included in the back.
All in all a wonderful collection for any Blake fan to own and for the curious to lose themselves in the majesty that is William Blake.