I\'m a recent convert. My last mini was paitned with one and is the highest ranked in my gallery, thought I\'m sure that\'s not all due to the wet pallet. I found it really helped keep my paints thin and let me keep blends longer.
I made mine myself using sponge, parchment paper and a container I picked up at Michaels. Unfortunately I didn\'t realize the lid of the container I picked was compartmentalized, which means that I can\'t put the lid on to save paint, as the compartments touch the paper and paint gets everywhere. So I can only tell you it keeps paint wet well while I am using it.
I do have a few issues with it though, mainly with getting the parchment to \'stick\' to the sponge and having sections lift up and dry out. So far I\'m guessing that\'s due to inexperience with the tool.