This is an impressive work, but a bit difficult to follow for those who aren't trained in linguistics (like your reviewer.) Knowing something about one of the Celtic languages is an enormous help. Russell starts with a general history of the Celtic languages, then examines Goidelic and Brittonic separately using Irish and Welsh as examples. The last section examines particular topics (e.g. lenition, word order) common to both branches. It's interesting to see how what is important to the professional linguist is not necessarily what strikes the amateur learner. This would, I think, benefit from a short section reviewing linguistic terminology and symbols for those of us who aren't pros. Still, this is well worth having for anyone interested in the "Celtic fringe." I read a Pearson Education Print on Demand edition.