This is a decent book about Brigid. Though I strongly recommend against going into this thinking the material is fully based in lore or historical truth. There seems to be a hefty dollop of UPG, but that's not necessity bad, as I'll get to shortly.
The author doesn't attempt to make Brigid into someone she's not, which is more than I can say about other authors and other goddesses. She uses the concept of "mother, maiden, crone" for Brigid, which isn't an idea that seems to actually have been in practice by the Celts of the distant past, but she isn't trying to say Brigid's just a wholly different deity than she really is that I recall, so props for that.
Acknowledging the Christian saint without totally trying to be a Christian apologist was nice to see.
The rituals and spells seem easy enough for a beginner and adaptable enough for a seasoned witch. So it won't matter if you only got started a short time ago or you've been practicing for years. These should work for you.
Now, why do I not consider UPG wholly bad? This is why: I personally believe seeing how gods and spirits communicate with different people can be useful. You get a broad sense of how the deity or spirit works and what their personality might be like when you see how they engage with different humans. You should never take someone's UPG as official. No 2 people will have the same experience. But I highly recommend reading other people's experiences to broaden your view. In this case, I don't recall the author trying to claim her experiences are official and she seemed to note where she added to something, expanded on something, or otherwise was speaking from a place of UPG. So she was being honest.
Anyway, I say this one gets a solid 3 stars. You could likely find better books from a more scholarly source, but this one still has value.