2 stars only because the Tech himself was good. We have been Knight clients for many years. They installed our furnace, water heater, and water softener a few years back and have been maintaining them ever since because we were happy with them, but that will end now.
First off, when looking at reviews, don't look at anything prior to a year or so ago. Knight used to have excellent customer service, admin, and follow-up. That is no longer the case and I think you'll see that in the reviews. Apparently ownership changed a while back and it seems to have seriously affected their customer service. Though their current rating looks OK, it is still being buoyed up by older reviews/ratings.
It's tedious to rehash all that went wrong with our recent attempts for annual maintenance, but it was multiple missed appointments in the 8am to Noon window with no call or text updates, or incorrect service invoices or assigning of Techs. After many years, we are done with Knight.