This set is based on the 72 Names of God, or Shemhamephoresh, a medieval Kabbalistic method in which a certain 3 Exodus Bible verses of 72 Hebrew letters each were written one on top of the other. Reading from top to bottom, 72 3-letter "names" were created. (The 3-Hebrew-letter names are used in the 72 Names of God by Rav Berg of the Kabbalah Centre of Madonna fame.) Christian Cabbalists Latinized these names and added "el" or "iah" to create angel names. Each angel is associated with a Psalms Bible verse, which gives the angel its specific meanings and "gifts." Each angel is also associated with a 5 degree portion of the astrological year (approximately 5 days). This form of Kabbalah is more widely known to French speakers than English speakers. (But I think the book for this set is translated from Italian!)
This background is complicated, but Angel Voices itself is pretty straightforward. Cards are numbered consecutively 1 through 80 (72 angels plus 7 archangels and the Angelic Palace). The angels are divided into 9 groups of 8 angels. Each group (called a "formation") is associated with a planet. Then each angel within the group is associated with a planet, so each angel has two planet symbols on its card, the formation planet on the left top and the angel planet on the right top. The 7 archangels and Angelic Palace have one planet each.
The formation planet determines the sky background of the card (angels of the Venus formation have a dawn pink sky, etc.) and the angel planet determines the angel's robe color (Mars angels have red robes, etc.). That is the only information the book gives about the pictures on the cards, which makes reading the cards very interesting! Some pictures obviously illustrate the angels' meanings: 17. Leviah, keyword rest, is seated in a rocking chair. Others are not as obvious: 58. Ieilael, keyword notoriety, is being handed a scroll by a mouse. My favorite enigmatic illustration: 60. Mizrael, keyword service, is kneeling to offer an apple to a beaver.
For each card/angel, the book provides a Keyword, Areas Concerned (study, love, etc.), Gifts (ways the angel helps people), Divinatory Significance, and Relevant Time Period (the 5-day period plus the days of the week ruled by the card's planets).
The book also provides brief divinatory sentences for each card for 10 pre-set spread positions. One spread has these 7 positions: person[ality], emotions, body, love, success, fortune, tests. Another spread has these 3 positions: talents, problem, outcome.
But the most interesting spreads (called "oracles") take advantage of the consecutive numbering of the cards. With the Oracle of Light and Shadow, you draw, say, card 21 to represent an issue, and then count to the 21st card after that to represent the "shadow" of that issue. With the Oracle of the Four Directions, you lay out a card for each direction and then average the card numbers (add and divide by four) to get the outcome card. (I immediately combined these two methods into a spread of my own!)
I suggest using the book Birth Angels: Fulfilling Your Life Purpose with the 72 Angels of the Kabbalah by Terah Cox (a French Canadian writing in English) in conjunction with this set for a more psychological/self-help slant on your readings.
I recommend Angel Voices for those of us who want some historical tradition behind our angel oracles. It has the advantage of many positive, spiritual meanings, as more contemporary angel oracles do, but it includes the negatives/shadows of life as well.