If you are still in school – force yourself to use it for a project. It is a simple program to learn if you already know AutoCad, especially with the command line. I watched the whole Lynda tutorial series (for a class/grade) but it wasn’t worth it. Just play around and try to make things! Also, I don’t know if you are using the Mac version or windows version – but the Windows version is 100x more powerful (and the Mac version is much harder to grasp and incredibly buggy).
Rhino is incredibly powerful, but if you only want to use simple forms and shapes it may not be worth the $$. But if you have any interest in computational / parametric design it cannot be beat.
Let me know if you have any other questions!
-Andrew