Generally this way of getting link does not give good result. Because when you sent an email to webmaster with high PR site, then they may not consider your email if your PR is low. But it may help in getting links from same PR sites.
it is completely depended upon your approach. how you approch to webmasters of others site ,there are so many factors that count in manually link building campaign. as domain, relevency of content, authenticity of information in your site and always your PR......
In link exchanges, I do it manually. I usually email webmasters and ask them if they're interested in doing reciprocal link exchanges. I'm not into using automated tools for they produce crappy links.