As I got a copy of this CDrom at a ridiculously low price it is hard to fault its value for money. While I agree with several other reviews that some of the practice clips are utterly laughable in their poor quality (several times I was clicking for a hazard I thought was a horse, when it was in fact a lamp post as it appeared as one big blurry pixel.)
Poor quality clips aside, I use this CD as a very useful tool in conjunction to a higher price DVD I purchased - some hazard perception clips of which were honestly no better quality. The layout of the theory test is also identical to the actual theory which is good if a sudden change of layout on the day might make you feel suddenly uncomfortable, the hazard perception clips also have a bar counting your clicks.
The CD is easily installed, easy to use and very responsive to my reactions and clicks. As I said, it would be good to revise and learn from a slightly higher quality product, but to test and consolidate your knowledge, this is definitely a good tool.