I used the slipcover over a memory foam mattress to be used in a sitting area with large pillows.  Since it is for large futons, I gave it a try on the mattress, which was pretty thick.  It was initially difficult, but I got in on.  It is really soft and the color is soft and neutral.  It also wipes and cleans off easily.

Pros: Good value, large size for mattress, soft and easy to wipe clean