It's different for all people. I've been on two exam board (WJEC and AQA). I found it fairly easily. It's good if you're a science-type of person that is also good at articulating themselves in essays. If not, I wouldn't be able to recommend it. WJEC for me is very easy and straight forward in comparison to other exam boards. With WJEC there is not much of either depth or breadth (in my opinion anyway). AQA there are a lot of things to cover but you don't necessarily go into depth for all of them, only some parts which is normal. This would better prepare someone that wants to study Psychology at university.
Psychology is hard to some people, and easy to others. It depends what your strengths are as an individual.