Only an Anglican would think it is possible to compile a book like this without favouring any particular point of view. It isn't, of course, and it doesn't; eg, on the sacraments there is one excerpt from Aquinas and four from Luther. On the whole I would say it leans towards Protestantism; even of the Catholic Fathers, the one most frequently cited is Augustine who doctrinally was something of a Prod precursor. On the other hand there are a few, like Hooker, who would probably not be interesting to any other denomination (it's a strange omission that there seems to be no reader of this kind concentrating on Catholic theology).
It's a book of mostly short excerpts obviously intended for students (my copy has a pencilled note saying 'good grief, you've lost me', besides a not-particularly-difficult passage of Augustine); the aim seems to be to provide them with easily-accessible quotes for their essays. They're so short that you'd be hard-pressed to get much out of them without the additional guidance of a set of lectures or a good textbook (of course, McGrath has helpfully also written a textbook).
It's certainly not 'a guide to salvation' as one review I saw says. It's like a treasure map in code: the goods are there, but how do you get at them? Maybe its best use would be to find out the books that might be worth reading in full, or at least in more substantial passages - as well as the excerpts themselves, there's a good 'further reading' section'. What drew me to this in the first place, though, is that original texts are expensive even 2nd hand, while this was only £2.50...