I've just finished my AS maths with edexcel.
I had a year out of maths because i did my GCSE a year early, and initially it was hard work getting back into it, especially as it is a huge leap from GCSE, but once you get into it, shouldn't be a problem. D1 is easy, core modules are harder. If you've done physics then you shouldn't find mechanics a problem. I'd say it's the same difficulty as other boards really, but the textbook often has questions much harder than anything that'll come up in the exam, and occasionally they print the wrong answer in the back which is frustrating...