Have you ever wondered why it is or isn't a good idea to e-File your taxes? 

Let's be honest, do you really want to tackle all the IRS forms without the help of a real live human being or software? Probably not. Tax preparation packages can walk you through almost every situation and I'd imagine a good percentage of Americans won't have any problems using it.  

Security and faster processing, are good reasons and Jim Wang in this article from US NEWS and WORLD REPORT gives you a few more

Income Tax