I set up my 45g brackish almost purely so I could get one of these. I also like puffers but the baby figure 8 I had died before I'd even gotten the violet goby and I haven't replaced it.
He's got a piece of slate leaning on the front for a cave that he sits or buries himself in often (black sand). Recently he dug out a decent pit under the driftwood and he spends a lot of his time under there now. He LOVES to tear pieces of algae off the driftwood and eat them and knows the moment the turkey baster hits the water! He props himself up and waits for the food.
The other fish in the tank are a bushynose pleco, 3 bumblebee gobies, a flame gourami, and river shrimp. The violet goby will let the bumblebees and the pleco hang out in his caves all they want but lunges at the gourami and any shrimp that try to come in.
I find him quite interesting, usually hiding but occasionally exploring or swimming and once in a while he sticks himself halfway up the glass with the bumbles for a bit. Even when he hides though, he peeks out a lot to see what's going on.