Does surprisingly well considering all it requires is your Twitter username to generate a list. Would be curious to see how well it works for people following a smaller number.
Works very well.. not sure it should have "should" in the name, but it's good enough for me to blog about: "Pistachio's "oneforty" and 10 Twitter Apps Worth Talking About" | social nerdia http://retwt.me/eyZY
Completely useless: 90+% of all the recommendations were similar to just ONE of the 134 people I follow, and even though I put the settings to "close to Busan, South Korea", 90+% of the people it recommended live in the US.
Very helpful... could have a richer UI but great for ideas of interesting people a degree or two removed.