To expound on what WG said, it is all about the quality of the release. You have to know how to write a good press release, and know how to optimize it.
We use PRWeb all the time, and we pay the few hundred extra for the bells and whistles . . . but again, we know how to write and optimize a press release correctly.
If done right, press releases can be the best link building you can do. This is the entire reason we started
www.PRadult.com