For the last couple years Michelle and I have relied on Turbo Tax when preparing our taxes. We used to have them prepared professionally but over time realized that we weren't getting our money's worth. Once you've gathered all your 1099's, W-2's, and maybe some random receipts, there's not much difference between typing the numbers in yourself and watching the person at H&R Block or Jackson Hewitt do it.
A few years ago in Florida we went to Carr, Riggs & Ingram in Niceville, thinking that a CPA would bring large benefits. I remember asking for a ballpark estimate up front and the man there told us it wouldn't be much more than H&R Block. That seemed great; a premium was understandable. A couple weeks later we were hit with a $600 bill. To make things worse, Michelle spotted an error on the return while we were sitting in the car outside, about to drive away. CRI fixed the issue but our refund wasn't any higher than the one Turbo Tax estimated for me at home.
Your mileage will surely vary, but once you've gathered all your papers, there's not much more left to do but enter the data.
I do occasionally have a question that confuses me deeply. Most recently I spent 30 minutes on the phone with the IRS trying to get an answer, and all they could do was read the official publications. I called a couple local CPAs and asked about paying them for, say, 30 minutes of their time (in reality it'd likely be 10 minutes). I didn't have high hopes for a call back, and I wasn't let down.
In the end I skipped taking the deduction because it was such a pain in the ass. Taking it may have saved us a few hundred dollars, but the CPA's fee would negate the benefit.