I would give that a hard pass. It gives very little info on the content that it is actually providing. If I had to guess its just a cheap android box with a bunch of crapware streaming apps on it. You could pull the same thing off for much cheaper, but the content is not worth it.
If you want to ditch att there are options depending on what you want to be able to watch. Streaming plans like Sling.com and the new direct tv streaming service are very economical options. The channel options vary, but the packages run from ~20-50 a month, no contract.
The major difference is you will be streaming it over the internet and you have to provide your own devices. (like a roku,amazon tv, apple tv, chromecast)Tons of info on https://www.reddit.com/r/cordcutters/ if you want to do some research.