I got one from Diver's Den and put it in a 20 gal nano (after quarantine).
Ate frozen food right away, and continues to do so.
Behaves like a hawkfish. Sits still but then will make sudden dashes for particular pieces of food.
Not very active but doesn't hide either.
Really nice fish; doesn't bother any other fish, and they don't bother it.
At least from this one fish, I wouldn't say they are difficult at all.
Probably better suited for a small tank though; might rarely see it in a big tank.