Like most SEO companies I have had details with they promise you the world, take your money and mess it up.
They promise expert service, no contract, cancellation any time, just payment in advance for each month.
They proceeded to write unintelligible SEO articles which would damage my company's reputation if I didn't completely rewrite them, and altered the core code on my website (which is a complete nono) which stopped my shopping cart working properly causing me lack of income before I figured it out, and cost having to employ a Magento consultant to fix it.
And when I cancelled they issued an invoice for another month's payment and passed it on to a firm of Florida debt collectors.
Oh, and after 5 months work on my keywords my traffic actually decreased.
Don't go near them! Review collected by and hosted on G2.com.