I don't think it's useful as a text message shortener because for me, my Android phone automatically sends 2 text messages. It will break the workflow if I have to click on a link to read the entire message that someone had sent.
As a tweet shortener, I know there's code to breaks a long message into chunks and tweets them so a link to read the entire message is again not ideal.
Best of luck :)
Thinking about getting rid of this domain/service. Do you find it useful?