You can like, or dislike, Anne Sexton. I won't describe her work (other reviewers have, and if you're here you're at least familiar), but say that if you've loved any poetry by Sexton, I highly recommend this book.
It's organized, chronologically, by her books (and hence her life): each poem from each book is within this one, plus some previously unpublished poems. Each of her books--in this case, chapters--is thematically consistent: fairy tales (Sexton-style "homages"), "love poems," time in the institution, etc.
You may not love every book/chapter, but the volume is a must-own. I don't see a need to buy "Love Poems," for example, or all or some of the rest of her books, when they're all in here - and each one not priced all that differently from this entirety. (It's also not oppressively long and hard to hold like some "complete" collections.)
Within this book, if you don't connect to one, two, or any of her other books, you've got them at hand and while enjoying the material you do--be it institution or masturbation--you'll be familiar with the rest.
Anne Sexton is my favorite poet, I admit, but when I reread a poem I far more often pick up this volume than the individual books.
As well, the chronological organization of "Complete Poems" tells a story itself - Sexton's life through her confessional poetry. It becomes a memoir, of sorts. While reading, you can easily see the year of each book's/chapter's publication. And in this way, the volume becomes a story and a biography.