Google really needs to make Google+ more exciting, the really simple and bland interface didn't really work here. Not everytime is simplicity better. People need to feel at home. Still the number of users on Google+ is increasing.
Google+ can't just die like that it hasn't even been out a year, the thing is that it is facing the toughest competition it has to ever face in the form of Facebook that is why the rate of popularity is a bit slow and people are finding it a bit difficult to make the transition.