You're probably not going to find recent scholarly reviews because the book is from 1997. It's a little bit dated. However, Barry Cunliffe is a hugely respected and important archaeologist who is a world-leading expert on European archaeology and the Celts. I'm not familiar with any monographs or books that discuss the topic in the same way.

Keep in mind a couple of things:

1. • It's not a Celtic history book but a book on Celtic archaeology. While archaeological evidence is undoubtedly useful to historians, archaeology is a completely different field of study (ask an archaeologist what they think about historians, especially about how historians use archaeological evidence - you're probably not going to get a positive response). Cunliffe uses historical sources but that's definitely not the focus of the book - the focus is on material culture of the Celts. Expect long discussions about types of pottery and torcs instead of examining narratives.
2. • It's very scholarly. I bought the book when I was 16 or 17, expecting it to be similar to the popular history books I'd already read, just with more pictures. That couldn't be further from the truth. While it was initially published by Penguin (I think a second edition is published by Oxford University Press?), it's not an easy read.

Overall, it's a very good book, but don't expect a light history book in the vein of Tom Holland - it's a serious scholarly work that happens to be a well-known book about a subject not usually touched on my popular historians.