I have 9 in use on my backyard patio in Eastern NC.
They are great for tomatoes, peppers, melons, and cukes. I also use one or two to try something different (for me), last year it was Blackberry bushes.
At the risk of inciting the wrath of the Moderators, I would point you to the EarthBox forum:
"forum dot earthbox dot com"
Lots of valuable information for growers interested in self-watering container gardening.