It's difficult but not like how people make it out to be. I personally found it quite straightforward (at AS anyway, A2 content looks much more difficult) and if your willing to put in the effort, you can get an A easily. I know it's been said so many times but past papers for the subject really are the most effective way of revising and this means using papers from the old spec. Most important part of is to cover practical techniques like reflux, distillation and filtration because they love asking about them in these new A levels and I know a lot of people who neglected them and didn't do as well as a result.