Well, what are your friends like?
You're asking one of those questions, and on the student room of all places!
Most of the people on here, and their friends, are straight As and A* candidates so in their eyes it would be amazingly easy - especially if they're also taking something like chemistry along side it.
One on my friends in the year above (13) got 2As 6Bs and 5Cs at GCSE...she got a D in psychology at AS (Actually no one at my sixth form got above a C at AS last year, will change this year with me I hope).
I'm finding psychology a lot of work actually, their is a hell of a lot to remember and i'm deadly serious about that. If you have a bad memory, I wouldn't even consider taking it. With psychology you don't even need to understand, it's all memory.
People at my sixth form say psychology is 'rock hard'. But then, everyone at my sixth form are idiots.