There is a time and place for advertising in the content network. When would that time be you ask?
Typically, we do not recommend advertising in the content network as we know from historical data that content does not convert into sales at the same percentage that search converts. However there is a reason to advertise in content. If you have a new product or brand name and you need massive exposure, content advertising can be excellent. If you expect sales from this exposure you may want to rethink your expectations of content advertising performance.
When advertising in content do not pay the full amount per click that you would pay in search. Google by default will enable content exposure at the same cost per click setting you select for search. With this particular tactic Google will rapidly soak up your cash so be careful about your budget.
In some cases to control the budget we will even set up separate campaigns for content advertising. Google does not recommend doing this, but their reason is really self serving. My feeling is that if you can control how much you spend in content and are able to clearly see what conversions come to you via the content network, you can adjust your advertising spend more appropriately.