they produce a risk-free search engine marketing campaign
Nothing in marketing is "risk free". Marketing is war and with war there is a risk. In this case, the risk is your dollar investment and your site's reputation.
Other than that, what they are offering in your statement doesn't sound like anything abnormal. You should check out the company's references, possibly ask for a sampling of the results they have obtained with some more difficult key phrases, see how readily available they are to you meaning do they respond quickly to your calls or emails, even check them out with the local BBB. Remember that if anything sounds too good to be true, it usually is. The statement you provided sounds okay but I did want to point out that all marketing carries a risk with it as none of the SEO companies in existence have any control over the search engines.
Good luck with your marketing efforts.