You do need good lung capacity and to be able to talk quite fast and very clearly, as well as, as you mentioned, having great rhythm and a good sense of flow in lyrics. It takes a different kind of skill than singing, that's all. I would not say it requires any less skill.
I'm not a huge fan of rap and most rap makes me cringe or want to kick something (mostly the person rapping for butchering rhythm, flow or language) but I don't like it when people degrade it just because they personally think it's a 'lesser' art form. You may have music in your very blood, rappers need rhythm in their very blood.

No, never even heard of it until now. Is it good? :0