This guy has a service that simply works.
I've been #3 and #2 for one medium difficulty keyword and ordered his service...now I'm #1 with around 30% indexation of the links. As more links get indexed, I expect to start automatically ranking for some even harder keywords.
Does his service bring rankings? Yes. On hard keywords? No way (you can't expect to rank for 'cheap insurance' using only this, common sense.) But on medium ones? Definitely!
BEST THING: the 3 links per account domain. Most guys out there have like 20-50 links per account, and VERY little link juice passes to your page. Here you have only 3 per account and I think this is the main advantage over the rest social bookmarking services.