I did my AS Core 1 in January (AQA) which i thought wasn't too challenging, it was GCSE standard for the most part. Core 2 though, which i've just done, was a different story.
I had my Mechanics 1 today as well. As i do Physics as well and because the topics overlap a lot in both Mechanics and Physics i found the Mechanics exam pretty simple for the most part purely because i've had a lot of practice in it in both subjects. I'm glad i didn't do Statistics though, i think i would have epic failed!
SpeedFreak, you can see some past papers on the AQA website if you like. In my Core 1 there was definately differentials, not sure about integrals, i think that was more Core 2 for me.