One word sums up this book - "thorough". The book genuinely covers everything that you will need to know to complete your CBT, pass the theory test and successfully pass your practical test.
Well presented throughout, with helpful pictures, diagrams and photos, this book is brilliant. The style of writing is pleasant, describing material in enough detail to be complete, but not so much as to become heavyweight.
The current edition of this book does now include the questions you may be asked in a 2008 theory test, as the book was revised with questions current from September 2007 onwards (at the time the number of questions in the test increased to 50). The current version (which I have) is ISBN #978-1844252206 and looks like that in the Amazon photo above.
Although you could pass the test with just this book, I would still recommend the Focus Multimedia Test Success Hazard Perception DVD-ROM and the official DSA Theory Test for Motorcyclists CD-ROM. This will ensure that you have experience of the mechanisms used to test you in the theory test.
I wouldn't recommend the DSA Theory Test for Motorcyclists book, which duplicates the questions at the back of "Learn to Ride". Nor would I recommend buying a copy of the Highway Code, as for learning purposes, you can read it on the DirectGov website.
In summary, if you can only get one book to help you pass your motorbike tests, make it this one.