I do not use it, because I would have to purchase it in bulk where I live, and I do not have enough storage space for it.
But, I would think that the liquid would be better to buy, because you can separate it into containers and freeze it for future use. I do not know how long the pre-whipped lasts in the bucket, or if you must store it in the refrigerator.
Anybody else?
Theresa 
I get Rich's Bettecreame and/or Pastry Pride at Smart & Final. It is non-dairy, so it is safe at room temp. I love using it as a filling (throw in a pudding mix to Pastrsy Pride - it's great) but I have never iced an entire cake with it. At Smart & Final it's in the freezer section - you thaw it overnight and then whip it up. I've never used the pre-whipped kind.
You should not cover a cake iced in Pastry Pride or Bettercream with fondant. Something about it makes the fondant break down. But, like I said, I use it as a filling with a nice buttercream dam and haven't had a problem.
I buy it in 1 quart bottles, like milk. I keep it frozen, use what I need and stick it back in the freezer. I've never tried it over fondant. I'd be afraid it was run off, but really don't know. I do know you DO NOT want to put if over Buttercream, that was a real mess, tried it once and it will NEVER happen again. I does whip up nicely and can be used to make flowers, too.
I use it all the time. I purchase it, prewhipped at Sam's club. It comes in 15 lb buckets. Before I had the space to store the large bucket, I would seperate it while still frozen into smaller containers.
It lasts almost a year unopened frozen and about 1-2 weeks thawed. It can sit out many hours without perishing as it is actually non dairy.
I wouldn't reccommend using it under fondant because it never "sets" and is very similar to stabilized whipped cream in consistency.
When I get it from Sam's, I call ahead and ask that they make sure to give me only what is still frozen and not already thawed because I cannot use such a large quantity in the couple of weeks time.
You can pipe with it, make roses and other flowers, color and add flavoring to it (although it already has a nice flavor).
You can purchase the liquid one that you have to whip up in quart size online from www.sugarcraft.com It is pourable liquid and not cold when you receive it, but according to the manufacturer, you can then refreeze it because it is shelf stable for up to 5 days unrefrigerated.
I ordered from them once, whipped it and was pleased, but I prefer the convenience of the prewhipped.
-Rezzy
ive tried both pre-whipped and the liquid .i prefer the liquid because you whip it to desired consistence and if you over whip just add a little more liquid and beat . and have tried the pre-whipped and dont like it any more ,only the first bucket i bought was ok ,the other 2 were very dry and over beaten very hard to the hand. so making borders with it is not pretty ,the icing breaks . I asked a friend who works at sams and she told me that it gets hard when your still working with it and that they have the same problems inside sams bakery
It appears that Rich's Bettercreme acts like whipping cream, so it's not suitable as a base for an entire cake covered in fondant; also other comments on Rich's Bettercreme and Pastry Pride:
http://www.cakecentral.com/cake-decorating-ftopict-27981-richs.html+bettercreme
http://www.cakecentral.com/cake-decorating-ftopict-51449-richs.html+bettercreme
http://www.cakecentral.com/cake-decorating-ftopict-44706-richs.html+bettercreme
HTH
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