Well it depends on the network, but generally;
Advantages:
* Protects you against click bombing if you were to get botted
* Audio library with a bunch of audio/sound effects available to you
* Forums (To learn, promote, collab, get ideas, etc.)
* Higher paying ads
* Licenses for games, and other things
* Partner support to answer any of the questions you have
* Possible Promotion (but don't count on it unless you are one of their big partners)
Disadvantages:
* Locked into the contract (Average 1-2 years)
* Cut in your pay