Just in case anyone is interested: I have been using this for 2 weeks now. It basically allows lots of easy social bookmarks (as most of you will know from free version). Around 60 sites are used in pro version, and you can do 25 urls a day. Then the article submissions go to about the same number of sites. So I have been writing quick articles and posting them, then bookmarking 5-10 of the live and not indexed articles a few days after submission.
The downside is that not many articles are indexed and they are always from same few sites that i've never heard of. Also the bookmarks are low quality and all same text.
The upside is that the submissions can be drip fed. Its a handy way of bookmarking web2.0 sites when needed.
Not sure if I'll continue as it is still quite time consuming, I'll probably opt to send articles to the bigger sites and just buy scrapebox blasts to web2.0's and other links. I have seen results but only on some easy pages. I think this is good for someone who writes lots of articles and needs to promote many sites. There will probably be some spaces at the beginning of june.