Another excellent volume in the 'Routledge Guidebook' series (see especially Morris's book on the Tractatus, Gardner on the Critique of Pure Reason). It provides an extremely clear and well-supported interpretation of the text which is subtle and sophisticated (and actually, at points, highly original) -- a perfect introduction for undergraduates. As with many of these Routledge Guidebooks, the book is extremely sympathetic to Wittgenstein (perhaps overly so), but as long as it is supplemented by other (more critical) interpretations -- as it should be regardless -- then there is little harm in this. In fact, its sympathetic reading really allows the beginner to 'think their way into' Wittgenstein's work. E.g. it really encourages the reader to take Wittgenstein's notion of grammar extremely seriously, and shows how this idea can be borne out with some success (if there's one phrase that summarises McGinn's own interpretation, it's *grammatical investigation*).
The book mentions some of the contemporary critical debates surrounding Wittgenstein's later philosophy (with useful chapter-by-chapter bibliographies), but I think it should be applauded for being primary concerned with the primary text itself (rather than a guide through the secondary literature -- we are reading about *Wittgenstein*, not Kripke's Wittgenstein, Hacker's Wittgenstein, or McDowell's Wittgenstein)
Excellent all in all --- I very much look forward the second edition.