At our school we're doing AQA Computing, and I didn't find the AS too difficult (got an A at AS). That said, I am one of the best of the class and most others have gotten C's or D's, with a couple of B's (out of a class of about 15). A2 on the other hand looks pretty difficult, we looked through a couple past papers and the syllabus at the end of Year 12 to give us an impression on A2 so we could decide whether we wanted to carry on. The coursework looks like a huge effort and the exam looks a huge step up from AS.That said, if you just want to do AS, and you think you'll enjoy computing, do it! Certainly my easiest subject (out of maths, physics, and history).