I saw it advertised on this site and it looks pretty nice.

I'm signed up for it and all, don't know if any providers are using it though.  Might stick with just my p411 and ditch it if the ladies don't jump on board.

Is there a cost involved?

Its OK but don't know if others use this app.

I'll stick with what I know works.  I'm never quick to try things like this.

I use all Apple products and the downloads will be in my history as long as I have the same account information. If you cloud with friends or spouses the app will be present.