My answer would begin with,

"You asked about TurboTax but I assume you mean any commercial tax software marketed to individuals, not professionals.  Frankly, TurboTax doesn't have much competition, but that doesn't make it any better than other programs.  If  the question is whether do-it-yourself taxpayers get better results using their home computer, rather than pen and ink -- my answer is definitely, yes.  I have seen too many people cheat themselves and pay too much tax, when they are relying only on the IRS instruction booklet.  But even software users can end up cheating themselves.  There are many more examples of how this can happen, than there are of situations where the IRS collects less..."