The UI is poor (FB isn't much better), but this will improve over time. A combination of third party tools, search engines and metadata (tagging) is needed to fully access it. Some of the interesting / useful interactions are narrowcasted, which is the opposite of the celebrity-driven content that comprises a large percent of the message traffic. Examples: tweeting during conferences, customer support for highly specific products or services, announcements from (smaller?) trusted sources, and time-dependent messages.