I saved this post to come back to once we had received our passports. I did use epassport photo. We took photos at home, cropped according to the tool and saved the file. I then uploaded the photos to snapfish and had them printed at our local Walgreens.
It was a completely painless process, very easy to use. I would do it again.
I do feel the need to mention though that the file you save has 4 of your picture and a green bar on the right side. It is formatted for a 4x6 print, which is great since the Department of State wants a 2x2 photo. I don't think the paper that our Walgreens used was a true 4x6 - only one of the 4 photos (on all 4 of our pictures) was an actual 2x2 that could be used by the state. So out of 16 pictures, only 4 were usable. That being said, I spent maybe 30 minutes taking shots of the 4 of us girls, uploading and purchasing prints for a total of $0.89. If I had to have the Post Office do photos while we were there because it didn't work, I didn't feel I was out any money. epassport photos does have an option to purchase your photos from them, I think it was $12 for 4? It was extremely similar in price to the Post Office and drug stores. (the possibility of it looking better is higher though!) The Department of State also has a tool (that I didn't use) to take your own photos.