The Twitter API is excellent in comparison, I guess in a way the newer Facebook API drew a lot of inspiration from it. Problem is it was rushed out and judging by the article and comments left here not much has happened documentation wise in the last 3 months or more since I last touched it.
You can do everything through the API that you can on twitter.com. In fact the new twitter.com site uses the API! One more thing, their API does what it says in the docs... when twitter is up ;-)