I recently read an article comparing the comprehension scores of the same content read on a desktop and on an iPhone. Not surprisingly, the comprehension scores from readers using an iPhone were 48% of those using a desktop. The article, written by Jakob Nielsen and can be found here, goes on to explain why readers would have a more difficult time understanding content on a mobile device versus a desktop device. The author also gives some good tips on how to improve comprehension of your content on mobile devices.
In conclusion he states, “complicated content should be rewritten to be shorter, with secondary information deferred to subsidiary pages.” While we often get wrapped up in visual design, I think understandability of content can be just as important.