I couldn't easily find out how to search based on city + age. When you click on search you end up in "All Twitter Users Nearby" and since I didn't see that tab, I couldn't understand why I wasn't seeing any age information nearby and why it was showing me guys! Then I discovered the other tab and found out how to make a real search but really, why is the default tab the one that isn't really "search"? It's confusing to click on search and you don't see any place to enter search criterias. Other than that, I really like the design and how easy it is to sign up! Keep up the good work