I guess that one of the problems of living in a cold, wet climate (as opposed to a hot, dry climate ala Egypt or much of Mexico), is that it's hard to leave behind a lot of stuff, especially if that stuff tends to decompose. One of the things that really struck me in this book (but which I, unfortunately, neglected to jot down the specific details of) was just how scanty some remains were ... five of this thing, fifteen of that, for all of Ireland. Almost all of what the archaeologists can point to are things deliberately dumped in some ritual context (in rivers, lakes, bogs, etc.) ... that would be almost like having no record of the Maya except for what was dredged out of the sacred Cenote at Chichen Itza! It also didn't help much that most of the "elite" (i.e., those who would be likely to have notable "grave goods") seemed to have been cremated rather than interred, meaning that there was a LOT less "stuff" to start with.
The book looks at major undertakings like the Hillforts, and the Corlea roadway, and notes that there is NO data on where the people who actually built these things lived. Even the major sites show only sporadic signs of being occupied. Much of what is attributed to the Irish in this period is based on other "Celtic" cultures, in Northern Europe (the "Hallstatt Culture" in Austria or the "La Tène Culture" in Switzerland), appearing in traces across the northern half of Ireland, with other influences (Iberian Celtic culture) showing up in the great fortifications in the southern half.
Given these caveats, Pagan Celtic Ireland is interesting enough, discussing what materials there are in detail, with a lot of helpful illustrations and photos. It is structured on major topics (political structure, technology and art, ritual and death, etc.) and looks at what can be said about these based on the actual surviving archaeological traces. Perhaps this is where the author stumbles ... were he to "riff" off of "what is known" and into speculation, it would have been a more vibrant read ... but limiting the "story line" to what could be defended by the minimal actual evidence kept things to a slow shuffle. Unfortunately, if you wanted to get a copy of this you're going to have to shell out about twenty bucks, either for the paperback via Amazon, or the hardcover used. Frankly, I'd recommend borrowing this one from the library first before spending the money.