Evidentia is to be used along side of your regular genealogy software to improve your research. It forces you to put in those sources and cite them as you go, instead of just putting down notes to write into "proper citations" later, as many of us are guilty of doing, at least some of the time. Instead of being focused on a particular person in your tree, it focuses on the sources. Once you fill in the information off of a source document, you can analyze the information for evidence and then it takes that information and helps you write a sound conclusion. The program is based on the Genealogical Proof Standard. That is what its purpose is, to make sure that you follow the GPS so that you'll get the most out of your research.
You can find out more and watch videos at the Evidentia blog. The program is inexpensive and can be purchased on their page. I got mine yesterday and am sure that it's going to be a very useful tool. It seems to be simple to learn. Check it out.