Tried to jack up my price 6 month in on a 24 month price guarantee plan.
Generally, the service barely holds together, with different parts of it not working reliably at any one time. Sometimes miscommunication on their part will result in you having no service at all, or you getting a wrong bill. Fixing it is where the nightmare starts.
The support agents are the worst. They have so many of them, but literally all of them are unable to help. And on the chat, they respond once in 5-10 minutes, so it will take hours until you reach the point that they can't help you.
One of the 10 times I was on the phone with them was funny. The guy's cow was mooing and singing while we talked. That was the best part of my entire experience with Comcast.