Ok, so I already have a great blender that can make smoothies- so why have this?  This makes it so much easier!  Rather than getting everything out with the big blender, I grab the cup, add the frozen fruit, fresh fruit, a little honey, add water, screw the lid on, and pop it on the base.  In a few moments it's done- unscrew the blade, screw on the lid, and voila - I have my smoothie cup.  

To me, I find myself having smoothies more often because this thing makes it more convenient to make them- rather than breaking out the large blender.  Having the cup you blend in being the same as what you drink from makes it really quick.  I work from home, so it really is a small time commitment to make one. Literally it's having a fresh smoothie in  a couple minutes.