In short and in solation the ATPLS are not difficult. As stated, it is the quantity that can be a problem. However, the danger subjects are Met and Gen Nav.
Met (and to a much lesser degree Principles of Flight) is just fuzzy logic and isn't feedback friendly simply because you have to consider the combined effects of several factors and then choose the best answer as there are usually several correct ones!!
The key to Gen Nav, from my experience, isn't brains but how quickly and accurately you can use the whizz-wheel.
The next biggest problem is reading the question properly
You'll be fine. Good luck
