I've been with them a few months, not particularly effective - but not particularly expensive either.
They DON'T get your website to the top of Google (as the salesman might lead you to believe), what they do is create a new website for you (called a Plink website) which they fill with keywords relating to places in a list you give them. They then check 4 times a month to see if this page is on page 1 of Google for each search term.
For every term that it IS on page 1, you get charged. The more obscure the term, the less you get charged. They cap your fees at about £30, so even if ALL your terms are on page 1 all month, you don't pay anymore than £30.
You have to be careful, because they'll suggest a list of about 50 keywords - and some of these will be for places that are out of your range of travel. So it's up to you to vet the list and make the necessary alterations.
So far, I've had one query which resulted in a very small rug clean (I charged £25, and it was the next street over from where I live), and been billed a grand total of £17.25 - so it's not been massively successful, but I'm guilty of ploughing my money into worse ventures!
The good thing is that on the Plink site, your contact details are partially hidden, so when someone clicks to reveal the rest of the details, you get a text message to say someone has requested your details.
If you want to know more, ask and I'll tryt my best to fill you in with an unbiased opinion.
Ash