The main thing you will be missing is Caller ID name (CNAM)
You can use various work arounds: CallCentric,
Simonics.com, etc if that is important to you
You can also use Google Voice for desktop texting
If something "breaks" you won't have Ma Bell, or Cox / Time Warner etc to call and fix
I suggest you put your router/modem/switch/obi on a UPS
If the power goes out, an old style phone that will work without being plugged in to house power is good to have.
also you will not be missing extra cash out of your pocket every month
Consider donating a % of your savings to your favorite charity