My feeling was that there was tiny, almost unnoticeable latency in the touchpad, the slightest of delays between sliding and the pointer responding. Not enough to impede productivity. Key strikes seemed about as responsive as a wired-in keyboard.
But it’s controlling your home entertainment gear that’s relevant here. How well it works is going to depend entirely on the gear. For example, I tried a HiSense TV, and the keyboard and trackpad worked fairly well in the web browser, albeit with enough milliseconds of delay to be slightly disconcerting. But it did nothing in the general smart interface. For that you have to go back to the regular remote control. A Samsung UltraHD Blu-ray player, though, supported the keyboard and trackpad quite extensively, allowing point and click across its interface, although the media control keys didn’t work back when playing content. There was also a little latency with the player, although somewhat less than with the TV.
Note, we’re talking tens of milliseconds here, not seconds, so with both devices it remained perfectly usable, so long as you’re not trying to play games which depend on quick responses.
A current model LG TV also offered fuller support, with almost complete integration. LG TVs are very pointer dependent, so this was welcome.
So in short, how much value you get out of the keyboard with your home entertainment system really is going to depend on the devices into which it is plugged.
The Logitech K830 keyboard isn’t cheap, so that’s something you might want to check out. Just take a standard USB computer keyboard and mouse and plug them into the TV or other smart device which you’re envisaging using with the keyboard and see how much control they provide. If you’re happy with that, then the Logitech K830 keyboard/trackpad combo is a great way of delivering that service.