My experience is while press releases are valuable marketing tools, press release services are worthless. I've done probably a dozen press releases utilizing some of the expensive services. Not once has a service been directly responsible for a write up or driven any substantial amount of traffic.

Identify your target audience of bloggers and writers and get your press release directly to them.

I wrote my experience with press releases here.

http://www.bigstartups.com/matt/blog/122/Effective-Ways-to-P...