The most difficult part was the computerized testing on programming. Most of the testing is generalized math/verbal-type stuff that's similar to the GRE/SAT (which was quite a while ago for me). However, you do have to code (or pseudocode) algorithms that do more than output "Hello world". Brush up on your programming mindset before showing up. They also have case studies... just keep in mind that medical professionals (the customers) don't trust anything that seems like it will jeopardize patient safety.