I decided to have a go with them a few weeks ago to push my Harriers-Online site click here a bit more.
It cost £5 to register and you then tell them how much you want to spend, in click through value, on your campaign. I went for 5p a click up to a limit of £2. Once that limit is reached you then set another campaign with either the same values or different ones.
You then set your ad up, which was quite easy, and then your keywords. These can be spelt whichever way you want taking into accout many people always spell incorrectly when searching. Your keywords also have to be case specific. Why, when Google isn't?
After that any matching search words or phrases from the punter that match your keywords will cause your ad to be shown on that page.
Now it gets complicated because if that keyword is not searched for a certain number of times each day Google then email you to tell you that it is under performing. You then have to either change that keyword for another one which you think will be more attractive OR change your expenditure rate to a higher one.
If they tell you 3 times or more, in a row, that your ad is under performing then you are charged another £5. etc...etc....
I had fifteen keywords and at the end of my first day I had my first email. The second was two days later. After checking my hit rate every five minutes on the third day I deleted the account.
Unless you have a big budget and a massively popular site then I'd steer clear. My site receives over 2000 hits a day and yet is still not good enough.