It turned out OK. The cover letter was pretty good, but didn't cover everything I needed it to say. It was still a struggle to rework it. But it was worth the $20 to get the process started.

My advice to someone trying this would be to understand that you'll probably need at least one revision. Check if revisions are included in the cost. In my case, they weren't, but he did a revision for me anyway. Also understand that you'll probably still need to rework it yourself anyway.

Oh, and I got an interview, so the cover letter must have been at least OK.

So, overall, it was a good value, but it wasn't like someone just wrote the cover letter for me and I had nothing to do.