I compared Twitter's own search engine with Twazzup - a third-party Twitter search engine, and went searching for tweets on Antarctica.
The difference between the two searches was vast.
Twitter's search engine was simple, reminding me of Google - "here's a list of Tweets with the word Antarctica in them. Here, too, is a random list of hot topics and searches totally unrelated to what you were looking for but we're tempting you with them anyway..."
Twazzup, on the other hand was much more. I could also view related images and the tweets that accompany them; popular Antarctica links and the tweets that accompany them; I could RT (re-tweet), reply, mouseover any link and then link directly to another tweet or link within THAT link... Sounds tricky. It wasn't. I liked it. I liked it very much.
And I found a tweet that linked to this YouTube video of a leopard seal killing penguins (unfortunate yes, but nature does what nature does) in an incredible display of nurturing survival. Awesome, I wish I was there.