I nearly switched to biochem half way through my bio major. I stayed with bio though, and I'm glad I did. Every school is different but I am sure the requirements, from school to school, are somewhat similar. Here is my view on the pros and cons (based specifically on how my school works, prob should do research into your own)
Biochem: As a biochem major you will fulfill all of your pre-med requirements without having to take additional classes. Although there are more core requirements, there are fewer biochem electives, meaning you have the freedom to take your upper level classes in just about anything you want (I knew a guy who did most of his 300 and 400 levels in English). However, biochem is, in my opinion, harder. I didn't want to take p-chem and all the additional biochem core classes.
Biology: Fewer core requirements, but requires a lot of upper level bio electives. This is good if that's what you want. I wanted to take immunology, virology, genetics, etc so it worked out. It also gives you the chance to take classes like animal behavior or ecology if that's your thing, because bio is a lot more than just cell structure, genetics, etc. Also, there are often a wider variety of bio classes to choose from. With bio, though, all of your pre-med requirements may not be met through the major (orgo II is not required for a bio major at my school). This probably won't be a big deal though, because I'm sure, at the most, there won't be more than 1-2 extra classes you'll need to take.