I got about halfway through the Savarese book and did ~100 COMBANK OMM questions (because I'm using COMQUEST for COMLEX study and didn't want to exhaust those).
I found it really easy. There were probably 50% of the questions that were quick and easy, 25% that required some thought/second-level decisions, 15% that were pretty hard, and 10% that were completely impossible. You're aiming for 50% (give or take a few) correct to pass, I believe (although it depends how your school grades it).
Just remember there are going to be a handful of questions that probably won't count (the fabled "test" questions.) Don't let them freak you out. Just move on.