Game of Thrones does a pretty good job with the iron throne, making it look impressive and have it serve its job. What it does not look like however, is a throne made of hundreds of weapons and one that would require a dragon to forge. And that is because the iron throne in the show is pretty different than the way George R.R. Martin, the author of the books imagines it.
The image you see above, an illustration by Marc Simonetti, is how Martin envisions the throne in his mind: a throne that looks scary and badass, and is not really comfortable to sit on, just the way Aegon Targaryen wanted his throne.