It's not bad, it's function is just limited since if you have 2 different camera angles or separate gameplay, it's taxing on the hardware in the same way VR, 3D, or splitscreen gaming is, meaning there must be compromises. It also means that unless games are made with it in mind, it's extra development for what may just be minor QoL features. The best ideas aren't necessarily game changing, but have specific use for certain types of games, not unlike motion control, which means some games just won't use it well.
I think assymetrical multiplayer was great, which is something people gushed over with PSVR and Playroom. Anything were people need separate (secret) screens can make for interesting gameplay, but there are better platforms for executing that (tablets, devices connecting online, or even separate Switches) but having that sort of functionality for a game on one device for local mutliplayer is at least intriguing.
Second screens for maps and inventory are usually pretty useful, as is removing HUD elements or creating extra shortcuts or buttons. The DS and 3DS have proved the concept well over the years. If anything, it just proved that looking between two separate screens an equal distance from your face are better than trying to shift focus between a Gamepad screen and a TV quickly.
For the record, playing Splatoon with a map on the Gamepad feels better than having to use a button to check on Splatoon 2. You'd think it would be quicker, and maybe it is when you don't want to take your eyes off the screen, but it's just as disorienting.
Again, I think these are idea that might work better if it wasn't a console and instead was a peripheral that can work like the Wii U but with a PC, or having tablets that everyone has that have games built with assymetrical multiplayer in mind. At this time, I think it's something Nintendo could, and should revisit, but some time in the future. The Switch can do some of that and maybe there is a cool way to bring back the Wii U concept but have it be reversed where the TV is the dummy display while the Switch is the console Gamepad.