Anyone used this service and in particular their SEO enhanced Press Release's? And what success is it likely to have?

I didn't think they had a specific SEO enhanced service. I think PRWeb is just natively search-friendly -- mostly meaning that you can include hyperlinks, and the releases stay around for a VERY long time. Also, the URLs have no parameters, and they use a title tag that matches the headline (though they use span's and not real h tags). Plus, it's free for their no-frills service.

The success is not always direct, but more indirect. People read your release, pick it up, post it as-is, and you've built a bunch of inbound links. Definitely helpful, and on the must-do list for SEO, but which news release service you choose can vary.

We can testify to the leverage PRWeb gives your Press Release. It's worth every dollar up to the $200 mark for sure. After that, I don't know, because we've never paid more than that. I don't know any better VALUE for Press Releases. -Dave

Actually, I've had pretty good success with PRWeb when I spent as little as $40. So, you don't necessarily have to spend $200 if your budget is limited.