This is certainly one of the clearer legal textbooks that I've read - it is very well laid out, separating out case and instrument extracts nicely and presented in a structure which makes notetaking very easy. Unfortunately it's substance is, in some key areas, rather flawed. Judicial Review in particular contains some rather confusing contradictions which are left unexplained, as well as some strongly opinionated views which, unless read in conjunction with other texts, could well be mistaken for fact due to the way in which they are presented. Sometimes this can veer dangerously close to misinformation. For example, the doctrine of manifest error is disregarded briefly as subjective, when in fact there is little case law to back this up. Indeed the only descriptions within dicta have referred to it as strictly objective, and the opinion that it is subjective is written as if factual, which would need to be substantiated before being dismissed in a similar way in an essay or exam.
Overall I would say that due to the shortage of good textbooks which are up to date with the Lisbon Treaty this is worth owning, but it should be read warily and possibly just to get an overview of a subject before using a less approachable text to take substantive notes.