Certainly not easiest of crustaceans, as they live in deeper areas than most commonly kept crabs and lobsters. I saw for first time a sign in a Czech aquarium but absolutely no giant isopods in the tank, probably they died but the signage remain - they shared the aquarium with horseshoe crabs and Japanese pineapple fishes, both still present.
In Japan there are a LOOOOT of aquariums with giant isopods of two species.
@Canihelpyou? not as difficult to keep as you'd think, giant isopods are quite hardy things. Their only requirement that could really be considered difficult is keeping the tank chilled to a suitably low temperature (10 degrees C or less). They require no specialised tank setup and are easily fed on anything meaty. Really no different care-wise to a similarly-sized lobster or crab, besides temperature.