I have had the 65" version of this TV for 2 years and have been happy with it as a 4K monitor.
The tablet remote is more of a gimmick than anything else - it is somewhat flimsy and very underpowered. The small standard remote gets used 95% of the time for input switching. The chromecast capabilities work fine from any android device, so we just use our phones when we want to throw youtube on the screen.
Wireless connectivity has been solid on 5GHz radio. No issues there.
I currently have a FireTV 4K pendant, a Razer laptop @ 3,840 x 2,160 and a Sony UBP-X800 UHD BR player hooked up without problems. Audio fed to a Denon AVR-X4100W over HDMI using ARC because the receiver doesn't support 4K video streams.
YMMV but I've been pleased.