Gmail certification test proved to be very challenging for me. I reviewed the advanced features today and practiced all the step-by-step exercises. Then I decided to take the exam. I was very surprised to see lots of questions that frankly I thought I didn't read from the lessons. At least I didn't remember them from the lessons. I answered them mostly from my experience of using Gmail. I used up almost ALL the 90 minutes allotted for the test and fortunately I passed.
My two cents to whomever is going in for this test: don't assume it's easy. Review ALL the lessons and practice the exercises. You would be glad you did!!!