The Imprisoned was an interesting take on a boss. Not only was he recurring, he was adaptable as well. His ability to grow arms and a tail were good enough to attempt a change in each fight (emphasis on attempt). As for the physical appearance of the boss, well, he wasn't too shabby, but still looked a bit ridiculous. I view him as a fat, stubby Godzilla... with white beans for fingernails and toenails.
But did I like fighting him? Absolutely not. It can easily get annoying to fight him after he grows more appendages, being able to stun Link as he presses upward to the Sealed Temple. Furthermore, the battles seemed repetitive, a possible exception being when he has the ability to fly. It just felt like busy work to fight him.
I guess you could say I really don't care for the thing.