I am not a philosopher or a theologian, and the Judaism I live every day doesn't need a clear concept of what happens when we die. In fact, I'm in tune with the strand of the Jewish tradition which actively discourages speculation on the topic. So, this book was an eye-opener for me. It shows that over time, Jews have answered the question "What happens when we die?" In many different ways.
In the TaNaCh, or Hebrew bible, you can find passages that imply we simply cease to exist, and passages that refer to a shadowy continued existence in an underworld (but nothing like the Hades of Greek myth or the Hell of Christian lore).
Later, you start to see two ideas, bodily resurrection and spiritual immortality, that coexist in various ways. At different times, different Jewish thinkers have believed:
1. We die and the breath of life leaves our bodies, but God will blow it back into us at the end of days and we will live again. (No mention of a soul)
2. Our bodies die, but our souls live on, closer or farther from God's glory, as we deserve. (No mention of resurrection)
3. We die and are immediately "resurrected" as souls, perhaps with some body-like qualities like personality, and we live forever in that manner. (In other words, immortality IS the way we come back to life.)
4. Our bodies die, and our souls are reincarnated.
5. Our bodies die, and "sparks" of our souls show up along with sparks of other souls in a new body and a new life.
6. The only immortality we have, or need, is in the influence and the memories we leave behind.
I find I personally believe in aspects of #3 and #6. But "believe" here means I trust, and I'm willing to live my life as if they were true--not that I am making any statements about the facts. I think that's what Gillman means by calling these beliefs "mythical." What matters is not the evidence for them but the ability they give us to order our chaotic lives in a meaningful way.
I would rate the book higher than the 3.5 stars I am assigning to it if it were more accessible to readers who don't know Jewish texts and Jewish history as well as I do. Even if you don't. It may be worth your while. It's a very smart and intellectually honest account of a topic that's not widely discussed.