I started with a 10pc set a few month ago and have been very pleased.  Since then, I have bought more pieces to complete the amount I'd like to have in the sizes I want. We find they're great for left-overs and you can clearly see what is in each container.  They stack nicely and efficiently in the fridge.  I've used in the microwave to reheat with no problem (without the top of course).  

For the person that mentioned stacking issues in the cabinet, I've found that I like to store the sizes individually, bottoms stacked and I place the lids vertically in the top container - works fine if you have the space to stack that way with less fuss about retrieving the size you want to use. 

For Rubbermaid, I'd love to see a rectangular size larger than the 4.7 cup but smaller than the 9.6 cup.  Thanks!