No offense but I shouldn't have to carry around an additional device(free or not) to do what current devices can already do on their own.
All though google voice has lots of cool features, I don't think its worth the hassle, at least not for me. I have had one too many issues with google voice to where my account was basically hijacked for several days up to a week at a time while google tried to figure out what was wrong, during that time I couldn't make or receive calls. Sprint's customer service was useless but it wasn't really their fault being that its always a google issue.
I really do hope that the note 3 has svlte, its a legitimate feature and it can easily be used by competitors to keep their customers from going to sprint. Hell, at&t had an iphone commercial about voice and data at the same time.