I've discussed this in particular reference to my work on this site. I think each gives a different level of expression to the same property. No matter how hard I've tried, my writing doesn't communicate the sex appeal of my characters as well as my fairly cartoony comic art does, perhaps because i've tried to keep the style a little free and easy and not super-realistic. There's an immediacy in visual art that prose can never communicate because you can ony describe certain features one at a time, or give approximations that don't communicate what makes the mental 'image' (and there's the key) instantly recognisable, but it works the other way as well.
I enjoy writing, and it's very useful for exploring the more abstract thoughts and feelings of a character that might seem too intrusive or indulgent in a comic. You can also be more allusory and evoke particular atmospheres with writing that don't always get explored in the visual world, especially sounds, tastes, and textures.
These ideas are only as applied to my own stories and characters, and both overlap to try and give a full sense of narrative and character. The only other thing i'd like to add is animating the stories and giving the characters voices. Animation is criminally undervalued in western society, and I owe Disney credit as the leading influence in how I draw facial expressions.