It runs off the internet, so you have to have that. If you don’t have internet, you can’t run Roku.
Roku runs off “channels.” SOME of those channels are live streaming (BYU TV, The Blaze TV, Wall Street Journal, BBC News, Al Jazeera….there’s likely a few more), but MOST are “pre-recorded” (Netflix, HuluPlus, etc.) All of the aforementioned (except for BlazeTV, NetFlix, Huluplus) are free. You can purchase streamed channels, but these are mostly games.
We use Roku in conjunction over-the-air antenna, antenna for live TV. Roku works with any type television (older standard def like we have, newer HD, or newest SmartTVs.)
You can take your ROKU box and plug it into any type television.
Roku just kicked off VideoBuzz which was a portal channel into YouTube, but allowed in Twonky, which (sort of) allows you to bounce your internet feed onto your larger TV.
If you are looking to replace cable with Roku, you need to decide what you can live without. You’re not going to find the Cooking Channel or Person of Interest on it. Ironically though, they do stream the Home Shopping Network 🙂
It has worked for us, but we were willing to eliminate cable/satellite and the option to “record” shows for later in order to not spend $67 a month on Dish network.