Angie's List customers are great because they pay for access to unbiased reviews and will often choose a higher priced company over a discounter. When you earn a high rating and get on their first page it can be a source of good clients. Unlike Yelp and CitySearch, there are no anonymous reviews so at least you won't have to deal with reviews posted by competitors and cranks.
I think it would be a rare Angie's Lister that would go past a page of A rated companies, and the site is set up so that it's hard to navigate to other pages. The problem then is, once they have a critical mass of cleaners/members in a certain area, your A rating isn't good enough and you'll have to pay to get back on the front page. The amount will vary by the number of members in your area, and you'll have to pay a fee for every specialty you want to list. They also will require you to give discounts to Angie's List members as part of your placement back on the front page. In our case, once we gave in and paid enough to get back on the front page, a dozen positive ratings suddenly showed up, including some that were months old. It seems like they either pressured some past customers for reviews or were holding some reviews back until we paid up.
Unbiased, it ain't.
PS: Yelp and City Search are not unbiased either. Impossible to remove anonymous crank reviews will disappear once you become an advertiser. Makes me wonder if crank reviews come from actual cranks or from their sales departments.