They're good for certain things, like the official Labo VR software and the little additions to games like BOTW and Captain Toad. I also used them for Virtual Boy emulation in Retroarch (needs a custom shader which is on this forum somewhere), which worked well, but now Red Viper is out on 3DS that's my preferred way to play VB.
Might be able to watch 3D movies with it, idk if it's been tried, but the same shader as for Retroarch might work if the media player homebrew can use it.
Compared to the official Labo VR headset, the unofficial ones offer a strap so you don't have to hold the headset up to your face (can remove the joycons for less weight), and the shaped plastic ones are likely to be more comfortable than the cardboard (and much cheaper than the official kit, you can pirate the Labo VR software if you want it).