This book is based for the OCR Biology AS exams, if you are on that board and doing the exams this book is all you will ever need (plus a little lecturer tuition). The book is simple to read well laid out, has great looking pictures (real and simulated) and also has some great tips in the CD for anyone looking to push through the A/A* barrier and struggling.
There are a few mistakes in this book as there often are but since this is the first edition and has only been running for three years it really is tops. The mistakes don't make a massive problem for students rather than making some simpler topics a little more ambiguous than they really are (nothing too much to worry about since any lecturer worth his/her salt should be able to right it again for you).
This book was my bible for Biology when I did my AS-Levels two years ago. The only reason I bought this book this time was because I sold the ones I had to my cousin since he was starting his A-Level Biology course as I finished mine, but after several months of not having this book at my disposal for checking certain facts I missed it enough to fork out for the AS and A2 books a second time despite the overall loss I made. I am very glad that I did since it has rekindled some of the happiest times in my education, cutting up lung in the labs and doing some tricky theory work in classes with my friends.
If you are not on the OCR board or are looking for some reading to do to jump start a lost education, I would say there are better books for the job. This book is very select in that it is for A-Levels and I'm sorry for anyone doing A-Levels now but this book doesn't break any records in terms of cutting edge science. I always felt A-Levels are like GCSEs on steroids, there is more to A-Levels but there is nothing there that is really really top end. Then again the only level of education you think is the best is the one you are on in the moment (degrees look harder than A-Levels because they are and A-Levels will look like a walk in the park after a masters degree in Biology is in your hand, right?). So if you are looking to push your knowledge of backtrack through your past then it is your choice, but for any OCR Biology AS Student this book is a 100% must.