Hello & Welcome

TIP: You should really introduce yourself properly before asking network questions. Yttalk gets those question everyday. I'm franky, an addict to the Fullscreen forums lol
Why join a network over youtube alone ? Because you have support behind you (i can talk with my partner manager Mon-Fri) , you get [sometimes , not in all networks] a dashboard to see all your earnings etc. & along with that a free (royalty free music , check your network)
You get branding [well everybody can have a banner now that the 1channel layout is forced] & modules (like Shows , Livestreaming etc.) instantly when you sign the contract / join. Also, if someone click bombs you & you're in a network , nothing will happen to you (it goes through the NETWORK not GOOGLE). Also, if you're a gamer or do cover songs (it's probably safe to say you don't have the licenses to those songs) & you monetize that video, it probably with come back with copyright. Machinima a licenses to games that allow their partners to upload gaming footage. Fullscreen has FAM (sub-network , only for musicians & artists) that lets their partners cover songs , worry free
If you want to learn more about networks , Please abuse the search bar
Am i partnered? Yes
With who? Fullscreen
Do i Like it? So far, yes
"Do i like it ?"is what you should be asking yourself when you get a contract form an network. Good luck