The more the iguana is used to people, the happier the iguana and the owner will be. There is much debate about the intelligence of reptiles, but iguanas certainly are clever. They can often be house-trained and will defecate in the same place each time. It is usually suggested that they don't have free roam of the house, although sometimes room-sized enclosures are made for them. A good compromise may be a cage or tank of reasonable size, and then letting the iguana roam the house for a few hours on a regular basis.
Iguanas definitely have different personalities, as do people and most house pets.
Iguanas can often be trained to ride on the owner's shoulder. With care and affection, most iguanas will be interesting and well-behaved pets. As with many animals, if they are well cared for and have everything that they need, they will normally not get sick. There is always a concern with animals that they might have some disease or problem that could affect their human owners. Also, pets sometimes get sick.