I really loved the three biology courses (molecular genomics, biochem, cell biology) provided by the IBMG program at School of Medicine. They are very intense and informative. However, the courses provided by School of Informatics were not so helpful. In many cases instructors just let students make presentations instead of giving lectures themselves. Probably that's because School of Informatics was founded not long ago.
The working intensity and enjoyability of research assistant really depends on the department and the lab. So be sure to ask current members before entering a lab. If you hear something like "hmm, the professor is strict on students", then it is possibly a hint for a mean professor. Remember that the relationship between a professor and a graduate student is like master and apprentice, which is very different from modern employment relationships. So a good professor can help you a lot, meanwhile, a bad professor can hurt you a lot.