I'm in year 13 and predicted A* and imo maths definitely has the reputation as being a challenging subject but it's one of those subjects where the grade you get is very proportional to the time you put in. If you've only done regular maths at GCSE level then nearly everything will be new to you and it will seem super confusing at the start but don't let this discourage you, the more you practice with textbook questions and past papers the easier it becomes
I highly recommend doing it because of how many degrees need maths but it comes down to what you want to study at university and which university you are aiming for