Well, my problems stem from mostly my teacher (who is nice, but her style makes the class a MILLION times harder for me, and I am far from a natural at math and science).
But the class (at least the AP at my school) just takes the rudimentary concepts I learned in regular physics frosh year and adding an extra depth and complexity. So it's like the first few sections of the chapter I can get, but the farther in I go the more confused and befuddled I get.
But I know a lot of people in my class who love it, so...my advice would be if you liked physics a lot, take it. But if you were only so-so with physics, see if you can sit in on a class or something or talk to people who have been in that class before.
Personally, I liked physics more than bio, but I wish I had taken AP Bio this year instead of AP Physics. But that's just me...
"If you can talk, you can sing...if you can walk, you can dance."
- T.K. Greene