It COMPLETELY depends on the course style. Some (most?) biochem I courses focus on fundamentals of protein synthesis and brute memorization of several metabolic pathways (Glycolysis, TCA, Cory, Pentose Phosphate, ect.) They tend to overwhelm the student, without providing much in the way of application or relevance, so its difficult.
Biochem II, usually revolves around more detailed aspects, like certain AA and NT synthesis and breakdown and their byproducts. Coenzymes, enzymatic mechanisms, kinetics, ect. Usually, II has more relevance for the world of biochemistry (although still may not be very clinically oriented).
I personally found II to be MUCH easier then I, but I am horrible at memorizing. I still can't name off all the enzymes in the TCA cycle - (despite learning it several times and having adv. degree in the subject).
I'd look at the syllabus and decide for yourself.