Mobile navigation can be difficult because you are forced to condense everything your site or app offers into a simple list or set of buttons. For the iPhone, three naviagational patterns rose up that are fairly good solutions to the problems of mobile navigation. You have the tab bar, the table view (like Messages or Mail), and the card stack, like what you find in Weather.
That doesn’t mean there aren’t designers trying other navigational solutions. Some of the more experimental ways to move around apps and sites work great, but there are some that just don’t work. Facebook’s mobile left nav flyout pattern is a perfect example of a mobile navigation system that should be gotten rid of.
Brent Jackson agrees that Facebook’s navigation system needs to be replaced, and argues why on his Tumblr page. More than anything, the issue I have with the system is it hides a lot of the functionality the app offers under small, hard to tap buttons.
As Jackson points out, the left nav flyout is also innefficient. While normally you have a small set of buttons always available to help you get where you want to be, Facebook makes you continuously wait for new lists or areas of the app to load. It becomes very tedious to do anything except look at the News Feed.
If you can think of times when a lefy nav flyout works, I’m all ears. There are none that work for me, or wouldn’t benefit from another site navigation system.