The title of the book may be a bit misleading. The book is not primarily focused on arguing for the deity of Christ (against, say Arian views of Jesus). This book is actually an extension of Swinburne's book 'Is There a God?'. In that book Swinburne argues for the plausibility of theism. In this book Swinburne argues for the plausibility of Christian theism.
So the book's argument is much broader than the deity of Jesus or the Trinity, though it does include arguments for both of those things. Richard Swinburne is a philosopher, not a theologian, and this book is argued purely from a philosophical angle. Christians who are looking for exegetical or theological arguments for the deity of Jesus should look elsewhere.
One might think that a philosophy book like this would be heavy reading. But it's actually very easy to follow, as far as method is concerned. The only difficulty readers may have is keeping track of all the steps along the process of Swinburne's thought. He moves simply, but quickly.
One also shouldn't expect Swinburne to offer very rigorous arguments in such a short book. For instance, his overall argument relies upon evidence for the resurrection. But Swinburne only sketches the argument on this topic. Anyone looking for a more robust case for the resurrection should look elsewhere. What Swinburne does is present a man-on-the-street version of the overall argument for Christian theism, attempting to show that it is plausible (which he repeatedly reminds the reader means 'not very improbable').
His argument for God being triune was very interesting. But it relies upon one accepting the doctrine of eternal generation. His theology is poor by Evangelical standards and will likely be rejected by any American Evangelical (Swinburne is British). For instance, he defends the Bible as entirely true by categorizing many books of the Bible as fables (historical fable, moral fable, or metaphysical fables) and promoting an allegorizing hermeneutic practiced by early church fathers like Origin and Augustine. If Swinburne were attempting to write a theology book or claiming to be a theologian I would give the book 1 star, but since it makes no pretense to that and since Swinburne's book is interesting, clear, and thoughtful I've given it four.