I got a B at AS and am continuing on to A2. It's fairly hard but all I will say is ask your teacher the moment you start to struggle, because once you fall behind it's a lot of work to catch up. Make sure to keep note of formulas taught to you by your teachers because they sometimes vary from those in the formula booklet and are far easier to use. And finally, past papers really are the best way to revise. All in all, it's not too much work as long as you try and keep up with the work and get in plenty of practice. My biggest problem this year was not putting enough work in outside of school and I was actually failing earlier this year.