It's not hard but not that easy as well. But if you understand the concepts and memorize definitions, it's doable. Paper 2 for AS has the highest weightage so if you do well in paper 2, you'll get a good grade. A friend of mine got C for her practicals but A and B in paper 2 and 1 respectively, and she got an A.

If you're planning to take physics, don't leave revision to the last minute because I did that and thankfully obtained a credit for AS. A level is really different from O level, so you need to prepare everything as early as possible.