Pros & Cons

Pros

You can generate an enormous amount of website traffic with little internal staffing.
You will get access to hundreds or thousands of internet marketers, eager to advertise for your organization.
Advertising-risk (except for set-up costs and monthly minimums) is transferred to the Affiliate.
You only pay Publishers when your objectives are met.
Instead of relying on the ideas of a small in-house staff, you have hundreds or thousands of internet marketing specialists using their creativity to promote your organization.
You can be selective when choosing your publishers.

Start-up costs (typically $5,000-$13,000) and monthly minimums (typically $500-$2,000) can be prohibitively high.
Highly qualified Affiliate Managers are hard to recruit and hire.
A poorly chosen Publisher could sully your reputation by sending out unwanted spam in your name or by placing your banner on inappropriate websites.
Conversion tracking is prone to occasional error (and upset Publishers).
Unless you use Publishers to create a mailing list, the publicity is not self-sustaining. The links to your site will disappear when you stop using the Publisher.
Most Affiliate Networks do not allow a trial period or a "money back guarantee." So, if you become quickly disenchanted with your Affiliate Program, you're set-up fee will be wasted and you may be contractually obligated to pay monthly minimums for a year or longer (depending on the negotiated terms of your contract).