they are common here in south FL, and they are pretty easy to keep, nothing special as far as water conditions go. They don't get too big, legs maybe 3 inches long each, and body size of a dime maybe a little bigger. They will eat any meaty foods that get down to the bottom, and mine eat small sinking pellets as well. They are extreamly variable in color, some being just grey and darker grey rather then the green and yellow, so make sure you are getting the right color form. The white and green you see in the photo isn't very common either, but IMO the yellow and green is better looking. The best looking one is red and yellow, but that is by far the least common of the color phases.
All in all it is a great star to have in your tank, but as noted they are very nocternal and shy so you will hardly ever see them. Besides that there isn't anything bad I can say about them as aquaruim inhabitants.