This is a really fantastic book for a certain type of person. That certain type of person is probably going to be Wiccan, which I happen to be. Wiccans generally love this book. If you are CR (Celtic Reconstructionist) you may have some issues with it, but many, many CRs really like the book too.
The first section is an overview of some history of the Celts which is very good. It's brief but accurate. The section on a year of celebrating the seasonal festivals is perhaps the most controversial. Kondratiev includes the 8 traditional Wiccan holidays with some nice suggestions for ritual. The problem of course is that the ancient Celts only celebrated the festivals that are used as the 4 major sabbats in Wicca and did not celebrate the solstices and equinoxes. But if one is Wicca, this may not be a concern. As long as one is aware of this, one will probably like the ritual ideas.
Probably my favorite chapter in the book is the one dealing with the lunar year. Kondratiev fully discloses that the meat of this section is purely his own invention. But what he has come up with for honoring the lunar cycle based on the Song of Amergin is lovely. At least I think so.
There is some great in this book and some not so great. How much you get out of it will really depend on your point of view. Many have criticized some of the political statements in the book. Some don't like his insistence upon learning a Celtic language....
I feel comfortable recommending the book to most people. If you are CR then you likely already have an opinion on it. If you are Wiccan and are interested in Celtic myth then it's good but don't let it be your last stop for information as it could mislead in some areas. Which is why I give it 4/5 stars. ( )

A great book for finding ideas for rituals and accurate information on Celtic history and holidays in the context of Celtic cultures and traditions. It's not the be-all and end-all of Celtic ritual but it's a good starting point. It's possible for both Celtic Pagans and Christians to use it.
Essential for anyone pursuing a Celtic path. One caveat, is that he does tend to lump all Celtic cultures together, it's important to see them as connected, but at the same time probably not appropriate to use all Celtic languages in the same rite! ( )