I took the class last summer. Don't waste your money. It will not help you that much. Plus the test at the end is about 10X easier than the actual questions you will see during Cell & Tissue.
If you really have nothing else to do but want to meet some of your future classmates and professors plus get a jump on some of the admin stuff and have money to burn then sign up otherwise enjoy your summer b/c you will get sick of seeing the building and the people. But that's just me.