RRP is £5.95 but this seems to be regularly available for under a fiver on Amazon. At that rate it's an excellent value for money revision tool for all GCSE Maths students.
Lots of video clips explaining topics and then example exam questions with a button to let you print and try the question yourself before you watch and see how it's done.
I think its particular strength is in helping students to learn independently of their teacher - for example if you get stuck on a past-paper exam question just look up the topic and see how it works.
Many videos have a small quirk (look out for the fight between presenters over who is going to answer one of the questions) which just lightens the mood enough to keep you revising a bit longer.
If you're on track for an A* then you might not find all of it so useful, but when you think what you'd pay a private tutor for this much help, I'd say this DVD-ROM is a great value investment. I've certainly recommended it to all my GCSE classes!