Has any one use Frostin Pride? If so how can i get it to be really smooth? 

Yes to your first question.  I use both Frostin Pride and Pastry Pride. For 2 reasons, I live in an area where many ppl prefer over buttercream and the cost.

How to get it smooth, Most people over whip the cream even tho the instructions tell you not to.  I think its because they are afraid if its not stiff it will not hold up.  Watch for the peaks to form, whip a little more and it will hold up fine.  Then, I also run a warm spatula over the cake and it smooths it out.  If you see crater like holes then take some liquid Frostin Pride (not whipped) and run it around, it will fill in the hole nicely.