I have used both the official Home Office handbook and the Life in the UK Test Study Guide 2012 with students hoping to take the Life in the UK Test, and the Study Guide is far better than the official handbook. I found that the Study Guide gave all the necessary information in a logical format and a good number of practice tests which were very close to the actual ones. For these reasons, it is probably contains all the information needed to pass the test at a reasonable price.
My only real objection is that it is not particularly well written. This was not too great a problem in a class where it could be explained in simpler terms, but may make it less suitable for self-study by people without reasonably good English. This is because it reproduces material from the badly-written Home Office, although the Study Guide adds side notes and diagrams which make it more accessible.
For all those who have to take the Life in the UK Test, this is probably your best resource.