having kept them in 2 tanks, and seen Msjinkxd's species tank in person, I think one of the keys to enjoying these crabs is to keep them in tanks with low light, lots of tall cover, and very little hardscape to hide in. If there's a rock to hide under, they will. If there's a cork wall to tuck into, they will. If you have a tank full of something like rotala, and nothing else, there's a much bigger chance of seeing them out and around.
Other than their tendency to hide in the dark, they are great to watch when they are out, and are truly easy to care for.
I've been wondering if an ideal tank for them would be a dark sand bottom with only frogbit. might not be exciting, but ought to be a lot easier to see them. Although, they are very similar in color to frogbit roots, so there's a chance you'd loose track of them as well..