I've had Insight for 6 years personally and at my parents' house since it was called Coaxial.
I've personally never had a problem with it, but for some reason their signal is very sensitive to the wiring in your house. My parents' were having issues with picture quality and Insight ran a new line from the pole to the house and it still didn't fix it. My parent's then got the wire that connected the outside to the junction inside replaced by a private company and they haven't had 1 problem since.
The only issue I ever had was when they used to shut everything down to run updates at night, but I haven't had that happen in ~3 years.