For one, their customer service sucks. If you call them(do they even still have a publicly available customer service # anymore? lol), they'll tell you for the residential unlimited plan "really does mean unlimited, no matter how many minutes you use." The problem with that is, it's a f'ing lie. If you use your voip too much they'll give you the "convienence" of upgrading your package(i.e. more money) without your permission. They'll upgrade your "residential unlimited plan"(as we all know unlimited in advertising means what the company deems is reasonable, not actually unlimited. contrary to what the workers said) to a business plan.
Even though it's cheap, that's more than enough reason for me to say don't ever go with packet8. Last I heard, they're quality was horrible and getting worst, but that could be wrong.