Anyone use this product?

Fill me in with how it works. Does it give you channels (how), or is it like a Tivo or Roku where you have to sign up for Netflix, Prime, etc, etc?

It is an Android TV device (now Google TV). That's it.
It is considered the best device for using Android TV, because of the memory and processing power.

It’s supposedly the best android box for IPTV.

I guess it saves to the cloud rather than to a HD then, and all programs are from Prime, Netflix, etc, etc.

Pretty much like Tivo except for where the recordings are stored.

IR codes available for URC?

Its more like a Roku than a Tivo. No Terrestrial tuner. Just aps

the Pro has an IR Receiver, Pretty sure the standard Shield does not.

Nvidia Shield Pro can run Plex server but one will have to add a USB hard drive for the Plex database. Plex has a TV tuner ability to watch and record terrestrial channels.

I have the Pro model and it runs every video codec and audio codec available and this is why it is considered the best streamer out there.

I'm not sure about the Pro having an IR sensor, but you could always use a FLIRC