I have been on it for coming up to 2 months now, I haven't had any headache or mood swings but have found my period started earlier than expected and carried on very lightly for an extra week, it wasn't any heavier than normal at the start but it carried on for close to 2 weeks, my period this month, touch wood, seems to be coming to an end a lot quicker. I saw a nurse about a month after starting for another reason and mentioned it to her and she said it was normal and if it carried on for the next few months to go back as there may be something else which suits me better.
I would recommend downloading the My OC app it recommends on the packaging if you think you may forget to take it exactly on time, I found it was very easy to forget but the app helps