The box is free to subscribers (although additional devices cost $120), can record up to 500 hours of TV and comes with Netflix and other streaming apps, much like Comcast's X1 cable box. Channel-wise, you can expect everything you'd find on DirecTV, although the new service doesn't have NFL Sunday Ticket. You don't need to be an AT&T internet or wireless customer to sign up.
So considering its similarities to an already-existing service, why bother launching AT&T TV at all? Costs, mainly, and declining viewing figures. As The Wall Street Journal reports, more than five million households in the US cut the pay-TV cord in 2019 -- the majority of which were DirecTV customers. Meanwhile, satellite TV involves fairly steep customer acquisition costs, namely in the form of gear installation. AT&T TV hardware, by comparison, can be self-installed by users. A basic AT&T TV package starts at $50 a month for a two-year contract. Like DirecTV, there are various upgrades and bolt-ons, and if you're an existing AT&T customer, some discounts to be had as well.
Update: 03/03/2020 4:15am ET -- This article has been updated to clarify that AT&T TV sign ups require an annual contract.