Severum are definitely cool fish and like stated before, their personality varies greatly from fish to fish. I've had/have 2 Sevs and 3 O's and I would not classify the Severum in the same category as my Oscars as far as wet pets.
Sure, they are more personable than say tetras or mollies but ime, they are not the wet pet, food begging drama queens that Oscars have proven themselves to be.
As stated before I have 2 Sev's, one Rotkiel and one Turquoise, the Rotkiel is a female and she stays in the shaded areas of my tank quite a bit, not skittish but not what I would call sociable. My turquoise male is a people watcher, he comes to the front and swims around quite a bit and even waits in the open to catch food at feeding time but I wouldn't call him a wet pet.
My 2 Oscars on the other hand are always in my face every time I walk up to the tank, wagging and dancing, begging for food and attention. They will happily snatch food from my hands and even splash me every once in a while; much more what I would consider a "wet-pet".