I didn't use it because I didn't see the point in paying someone to do something in 10 days that I could do by myself in an hour and a half. It's tedious, yes, but not difficult. I'd much rather enter it myself then use the $65 to get a nice dinner to celebrate being done with it.
That being said, unless you plan to get your app sent in immediately when AACOMAS opens, it wouldn't be a major disadvantage for you.
I can't speak for this process directly, but I do know of two people who used this method and it took well over 10 days to get the grades entered into the system and verified. I just did it myself. Just type in exactly what it says and exactly the grade and number of credit hours for every single class during the correct time-frame and you should be golden. I had no issues with self-entry.