Easy to use. I have used H&R Block's product for several years and like the ease with which I can forward data from previous years, especially helpful when carrying capital gains and tax credits forward I have confidence in the results and always feel not only that I have gotten the maximum in refunds, but also understand why.
When filing state online, it gets confusing because they say at the last minute you need to include copies of certain documents. That needs to be automatic. Not an extra step.