Biochem here is not in the same league as Gross Anatomy. Still harder than undergrad Biochem, but much easier than G.A.
There are 3 reasons G.A. is so difficult in dental school.
1) You have to memorize thousands of items for each test. As PDizzle points out, it is much more than ID. ID is really the easiest part.
2) The tests are on a blank sheet, not multiple choice. You have to REALLY memorize everything.
3) The stations are timed. Once that bell goes off, you're done. Things can snowball very quickly.
The timed stations were my biggest problem in the course. You're at a station with about 6 questions, and you have 2 minutes to answer them. My brain doesn't always work that quickly.
Timed stations aside, the course was pretty manageable until we got to head/neck. Head/neck was nuts. A real kick in the balls. I think all my classmates would agree it is the most difficult test in first year.
Every school's GA is different though. For example NYU has plasticized cadavers. I think this would make the course much easier, because you only see ideal dissections. I'm not sure how it is taught at the undergrad level, but I'm skeptical. There also seem to be some people that have very good memorization skills. Only a few though. I swear one of my friends can memorize like this guy:
http://en.wikipedia.org/wiki/Kim_Peek
It sounds silly, but
that dude would be a model dental student. He has an IQ of 87, but he can memorize. That's what dental school's all about. You will probably be frustrated and bored if you are the math type.