I took it in my sophomore year. Mathematics was hard for me, whereas English was easy. Biology was confusing and there were terms that I didn't understand. Filipino and AP lulled me meanwhile. Overall, I'd say the whole test was somewhere in between. I didn't really take it too seriously.
I believe that as long as you have stock knowledge, you'll be fine. But if you really, really want to rank first among all your batchmates, then you'd have to study really hard.