It was ok, but I must warn you, also very difficult. I certainly didn't manage to finish the paper in time, making it quite possibly the hardest exam I've ever taken (with the possible exception of Latin Literature)... The textbook is good, but I'd recommend going over it as you go until you know it all thoroughly... my problem was that I finished the textbook by Christmas, and then went slack for several months, meaning that I had to spend the weeks leading up to the exam madly going through the book again! So pace yourself.
But on the brighter side, it was probably also the most fun exam I've taken (again, if you don't count UKMT stuff) - the challenge gave it spice, and it was very rewarding to solve the questions. The OCR textbook I used (I assume you probably have the same one) had 14 topics; in the exam, there was one question per topic, so don't expect too many gimme questions!
The basic advice I'd give, and the advice my dad (who is a mathematician) always gives, is to understand everything so thoroughly that you could answer any question on the topic quickly, knowing automatically what to do. And the best way to do this is practice. Maths is one of the few subjects in which you don't need to memorise tonnes of info, but you do need to make the most of the questions in the textbook (and past paper questions) to practice... if you're doing this with a teacher, then ask them for as many questions as they can get hold of on the topics - that's how you ace it
Anyway, have fun! If you enjoy maths (and I'm assuming you do), then you'll probably love the course, and it will give you a massive head-start when it comes to A-level maths, as you'll basically know everything in the first year!