Why am I using it? Because Echofon is now paid ($20) and present ads in the free version. While I agree with the need of revenue, I do not like to have the ad where it is placed, making the application usage quite strange. Also, as I do not think Echofon is exactly what I want to Tweet, and as probably Tweeter will get paid sooner or later, I decided to try another application instead of buying it.
Noticed a friend that was using YoruFukurou as twitter client. Liked the name, and googled. It is very similar in format with Echofon, but the latest has a more polished user interface. In the other hand, YoruFukurou is very customizable and does not present any ad.