Eric Day, who had invented the new application Siri0us has pulled it from Cydia, probably due to issues related to copyright.
Some people think that Siri0us can do everything that Siri can. However, this is not true.
Siri0us is a combination of softwares. Though it uses official iPhone 4S GUI, it uses Nuance to recognize your voice and put in text format on the screen of iPhone 4S.
Ever since Siri0us has been released, the servers of if0rce have been crashing on and off. There is a theory that this is happening due to a large number of people are trying to download it. Siri0us is only dictation. It cannot talk to you the way Siri can.
Following video can tell you about the limitations of Siri0us.